Self-Clumping Cat Litter

ABSTRACT

A litter and litter making method producing cat litter from a carbohydrate starch-containing cereal grain, e.g., corn, based admixture extruded from a single screw or twin screw extruder forming pellets having a clumping agent formed during extrusion composed at least in part of carbohydrate polymer binder. Each pellet is extruded under conditions that cause formation of carbohydrate polymer binder clumping agent at least some of which is water soluble. One preferred method of extruding cat litter causes starch dextrinization to occur such that at least some of the carbohydrate polymer binder clumping agent in each pellet is formed of dextrin. Each pellet can be coated such as with a smectite that preferably is bentonite. During use, pellet extrusion formed clumping agent in a pellet wetted with urine dissolves and flows in between and along adjacent pellets causing them to clump together without the presence of any clumping agent additive.

CROSS REFERENCE

This application is a continuation of U.S. application Ser. No.13/842,534, filed Mar. 15, 2013, which claims priority under 35 U.S.C.§119(e) in U.S. Provisional Patent Application No. 61/775,707, filedMar. 11, 2013 and in U.S. Provisional Patent Application No. 61/699,858,filed Sep. 11, 2012, the entirety of each of which are hereby expresslyincorporated herein by reference.

FIELD

The present invention is directed to cat litter and more particularly toa self-clumping cat litter having a clumping agent formed of the catlitter from the making of the cat litter.

BACKGROUND

While attempts have been made in the past to produce a lighter, morenatural, and even biodegradable cat litter, improvements nonethelessremain desirable. Conventional clay-based and gel-based litters arerelatively heavy, cost a considerable amount of money to ship, and areoften a burden for purchasers to carry. While many so-called natural catlitters have been introduced into the marketplace, they can be nearly asheavy as conventional litter, typically absorb far less urine thanconventional litter, can produce their own unpleasant odor, and manytimes do not clump well, if they even clump at all.

SUMMARY

The present invention is directed to pet or animal litter, preferablycat litter, formed of litter grains comprised of extrudedstarch-containing pellets that each have a plurality of pairs ofinternal voids that aid liquid absorption and which have an outersurface that can be porous having a plurality of pores and whichincludes a water soluble carbohydrate polymer binder formed duringextrusion that functions as a clumping agent to clump adjacent pelletstogether when wetted with liquid. The pellets produce granular litterhaving a bulk density at least 40% less than the bulk density ofconventional clay-based cat litters and weigh no more than half theweight of conventional clay-based cat litter for a given volume. Thepellets have a starch content of at least 40% by weight such that thecombination of pores, voids and starch grains work synergistically toproduce a lightweight cat litter that has an absorptive capacity forabsorbing urine, moisture from fecal matter, water and other liquidssubstantially at least as great as conventional clay-based cat litter ona per weight basis and possesses at least 70% the absorptive capacity ofconventional clay-based cat litter on a per volume basis.

Each pellet has a clumping agent produced during gelatinization and/orextrusion of a high-carbohydrate admixture containing at least 45%carbohydrates by weight where at least some of the starch present isconverted during gelatinization and./or extrusion during processing in asingle screw or twin screw extruder into a clumping agent in the form ofa carbohydrate polymer binder that can include or be composed of watersoluble dextrin. In a preferred pellet embodiment, each pellet is formedof a high-starch admixture containing at least 45% starch by weight thatproduces such a carbohydrate polymer binder clumping agent duringextrusion that preferably is water soluble enabling at least some binderto dissolve in urine, moisture from fecal matter, water or anotherliquid wetting a litter pellet and flow along the pellet in between oneor more adjacent pellets at least loosely bending the adjacent pelletsclumping them together.

Each pellet is round or oblong and can be generally cylindrical formedof natural or plant based constituents producing litter pellets ofbiodegradable composition. Each pellet has a width or diameter rangingbetween 1 millimeter and 10 millimeters and a length of between 1millimeter and 10 millimeters enabling a plurality of pairs of rows andcolumns of litter pellets a plurality of pairs of layers deep to be usedin a litter box producing litter grains of a similar size and shape tothat of conventional clay-based litter.

Each pellet can include a treatment added, mixed or otherwise blendedwith the admixture in the form of one or more of an odor inhibitor, aurea degradation inhibitor, a urease formation inhibitor, a bacterialinhibitor, a fungal growth inhibitor, a yeast growth inhibitor, ananti-parasitic treatment, an antiviral, a scent, a fragrance, or anothertreatment before extrusion. Each pellet can be treated after extrusionwith one of such treatments such as by dusting, misting, spraying,agglomerating, plating, coating or otherwise applying one or more suchtreatments to each pellet.

Each pellet can be coated with a coating that increases pellet crushstrength, imparts each pellet with an appearance, texture and feelsimilar to or substantially the same as conventional clay-based littergranules, forms a shell around each pellet having a hardness greaterthan that of the pellet, substantially completely encapsulates eachpellet, and/or complements the pellet by giving the pellet one or moreabsorptive, odor control, antibacterial, antifungal, anti-yeast,antiviral, anti-parasitic or other properties not already present in thepellet. In a preferred embodiment, the coating includes an absorbentmaterial, such as a smectite that preferably is a bentonite clay,preferably sodium bentonite, and which can include zeolite, sodiumbicarbonate and/or calcium bicarbonate, along with silica, e.g.,crystalline silica, that is applied in a manner that coats each pelletwith a coating having at least 70% by coating weight of the smectitethat is between 0.05 millimeter and 1 millimeter thick and preferably atleast 0.1 millimeter thick.

The pellets are made from a relatively high carbohydrate high starchadmixture having a relatively low moisture content of less than 15% byweight, and preferably less than 11% by weight, when gelatinized andextruded by a single screw extruder under a relatively high extruderpressure of at least 800 pounds per square inch (psi) and an extrudertemperature of at least 135° Celsius (about 275° Fahrenheit) thatproduces carbohydrate polymer binder clumping agent during extrusionthat self-clumps pellets when wetted with urine, moisture from fecalmatter, water or another liquid. In a preferred method of making litterpellets in accordance with the invention, the admixture is gelatinizedand extruded at a pressure of at least 900 psi, preferably between900-1200 psi, and at a temperature of at least 140° Celsius (about 284°Fahrenheit), preferably between 140° Celsius (about 284° Fahrenheit) and165° Celsius (about 330° Fahrenheit).

When extruded under such conditions, starch carbohydrate polymer binderformation can and preferably does occur that can include starchdextrinization forming at least 1% by weight of a water solublecarbohydrate polymer binder clumping agent that preferably is orincludes dextrin. Preferably under such extrusion conditions andextruder operating parameters adiabatic extrusion occurs causing starchdextrinization to occur during extrusion forming a sufficient amount ofdextrin in each pellet greater than 0.1% of pellet weight that functionsas a clumping agent during pet or animal litter use. In a preferredmethod, extrusion under such conditions produces between 1% and 10%carbohydrate polymer binder clumping agent that can be partially orsubstantially completely composed of dextrin.

A preferred admixture is formed of at least 50% by dry mixture weight ofa high carbohydrate cereal grain having a carbohydrate content of atleast 45% of cereal grain weight that also is of high starch contenthaving a starch content of at least 45%. Suitable cereal grains includeone or more of corn or maize, rice, wheat, triticale, amaranth, and/orsorghum with each cereal grain being particle size reduced or comminutedin grit, meal, starch, or flour form. The admixture can includecellulosic material in an amount of no more than 50% of dry admixtureweight having a cellulose content of at least 20% by cellulosic materialweight. In at least one admixture, no cellulosic material is used withat least 80% of the dry admixture formed of one or more particle sizereduced or comminuted cereal grains mixed or blended together in a mixeror blender to which water can be added, such as to activate one or moreof the cereal grains and/or constituent(s) of the grains including oneor more of starch(es), sugar(s), protein(s), and/or the like. Water canalso be added to the admixture in the extruder including duringgelatinization of the admixture if desired.

The gelatinized admixture is extruded from the extruder at pressures andtemperatures in accordance with that discussed above formingcarbohydrate polymer binder clumping agent in each pellet producing aplurality of pairs of pairs per minute and preferably producing at least150-200 pounds of such pellets per hour. A preferred extruderparticularly well suited for producing such pellets at a desired minimumpound per hour rate at a desired consistency and uniformity is a singlescrew extruder equipped with a compression screw or a screw having oneor more compressor sections or zones that help keep extrusion pressuresand temperatures relatively constant within a desired aforementionedrange(s).

Such extruder operating conditions and parameters not only form pelletscontaining carbohydrate polymer binder clumping agent but also causeeach pellet to expand or puff like puffed rice or popcorn during andafter extrusion. Depending on the pellet density desired, apost-extrusion pellet expansion or puffing control step can be performedimmediately after extrusion that limits post-extrusion expansion orpuffing and which can positively impact starch re-crystallization and/orretrogradation. Where such a post-extrusion pellet expansion or puffingcontrol step is performed, pellets exiting the extruder are held in acontainer allowing between 5 pound and 50 pounds of extruded pellets tobe gathered together in contact with one another for a period of between5 minutes and 45 minutes before the expansion or puffing stabilizedpellets are transferred.

The pellets can be treated or coated right after extrusion or afterpost-extrusion expansion or puffing stabilization is performed whichsuch a step is desired or needed. Where the pellets are treated afterextrusion, the treatment can be applied to the pellets before and/orduring an agglomeration, plating or coating step where each pellet iscoated with a coating like the smectite, e.g., bentonite, coatingdiscussed above. Where a post-extrusion treatment step is performed, oneor more of an odor inhibitor, a urea degradation inhibitor, a ureaseformation inhibitor, a bacterial inhibitor, a fungal growth inhibitor, ayeast growth inhibitor, an anti-parasitic treatment, an antiviral, ascent, a fragrance, or another treatment can be applied directly to thepellets, such as by dusting, misting, spraying, coating or the like.Such a post-extrusion treatment step can be performed while the pelletsare in an agglomerator, coating tumbler or the like that can agitate ormove the pellets during application of the one or more treatments.

Where performed as part of the coating step, the one or more treatmentscan be mixed, entrained, and/or dissolved in a liquid that can alsocontain one or more constituents of the coating and/or which can be usedto wet, tackify, or otherwise increase coating adherence during thecoating step. The coating step is performed in one or moreagglomerators, plating devices, and/or coating tumblers until thepellets are desirably coated.

If desired, one or more drying steps can be performed after extrusionand/or after coating. One or more stabilization steps can also beperformed, where uncoated and/or coated pellets are held at a desiredtemperature and/or humidity for a desired period of time. In onepreferred stabilization step, pellets extruded fall into a containerwhere the pellets are held in contact with one another for either apredetermined period of time or time range or until the pellets cool toa predetermined temperature or until their temperature is within apredetermined temperature range before the pellets are transferred foradditional post-extrusion processing, like treatment, coating, dryingand/or packaging.

The pellets, whether coated or uncoated, are packaged for shipment andretail sale in bags, containers, boxes, or the like that can beair-tightly sealed along with one or more packets of a desiccant whereit is desired to maintain the packaged litter pellets at or below adesired moisture level during shipment, storage and prior to consumeruse. If desired, one or more packets of a humectant can be packaged withthe pellets in addition to or instead of desiccant packets where it isdesired to maintain the packaged litter pellets at or above a desiredmoisture level during shipment, storage and prior to consumer use. Suchpackets help maintain pellet absorbency and performance for an extendedperiod of time and can help extend shelf life by slowing or stoppingstarch re-crystallization and/or retrogradation.

In one preferred method of making cat litter an admixture that includesstarch is gelatinized in an extruder under sufficient pressure andtemperature causing a litter clumping agent to form that includes acarbohydrate polymer binder formed of at least some of the starch in theadmixture during extrusion from the extruder producing a plurality ofextruded litter pellets having a bulk density no greater than 0.7 gramsper cubic centimeter having carbohydrate polymer binder clumping agentthat preferably is water soluble. In one preferred method, at leastpart, if not all, of the carbohydrate polymer binder clumping agentincludes or is formed of dextrin.

During operation of the extruder in carrying out the method of makinglitter, the admixture (after any water has been added) has a moisturecontent low enough and the extruder operates at an extrusion pressureand temperature high enough to dextrinize starch in the admixture duringat least one of gelatinization and extrusion by the extruder formingdextrin in each litter pellet. In one preferred implementation of themethod, the admixture (after any water has been added, i.e. wetadmixture) has a moisture content of no more than 18% by total wetadmixture weight and the extruder extrudes the plurality of litterpellets at an extrusion pressure of at least 800 pounds per square inchand at extrusion temperature of at least 135° Celsius. Under suchextruder operating conditions, the extruder operates under adiabaticextruder operating conditions during extruding the plurality of litterpellets.

One such method of making litter produces litter pellets each having atleast 0.1% dextrin by weight. Another such method produces litterpellets each having at least 2% dextrin by weight. Still another suchmethod produces litter pellets each having between 0.1% and 5% dextrinby weight. Another such method produces litter pellets each havingbetween 2% and 10% dextrin by weight.

One preferred admixture well suited for use with a method of making ofmaking litter has at least one cereal grain with a high carbohydratecontent of at least 45% by cereal grain weight. Such an admixture can beformed of at least 70% by dry admixture weight of at least one cerealgrain having a high carbohydrate content of at least 45% by cereal grainweight. When extruded in accordance with a method of making litter ofthe present invention, each one of the plurality of litter pelletsproduced has at least 1% of carbohydrate polymer clumping agent byuncoated pellet weight and preferably between 1% and 10% carbohydratepolymer clumping agent with at least some of the carbohydrate polymerclumping agent being water soluble.

One such preferred admixture (after any water has been added, i.e. wetadmixture) has a moisture content of no more than about 10% by total wetadmixture weight and the extruder extrudes the plurality of litterpellets at an extrusion pressure of at least 600 pounds per square inchand at extrusion temperature of at least 135° Celsius. The admixture canbe made of a dry admixture formed of at least 70% by dry admixtureweight of at least one cereal grain having a high carbohydrate contentof at least 65% by cereal grain weight and having a high starch contentof at least 60% by cereal grain weight. One such preferred dry admixturehas at least 70% corn by dry admixture weight (before any water is addedto the admixture) with suitable sources of corn including at least ofcorn grits, corn meal, corn flour and corn starch and which can includea blend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

Another preferred admixture (after any water has been added, i.e. wetadmixture) producing extruded litter pellets having between 1% and 10%carbohydrate polymer binder clumping agent by pellet weight has amoisture content of no more than about 18% by total wet admixture weightand the extruder extrudes the plurality of litter pellets at anextrusion pressure of at least 800 pounds per square inch and atextrusion temperature of at least 135° Celsius. The admixture can bemade of a dry admixture formed of at least 70% by dry admixture weightof at least one cereal grain having a high carbohydrate content of atleast 65% by cereal grain weight and having a high starch content of atleast 60% by cereal grain weight. One such preferred dry admixture hasat least 70% corn by dry admixture weight (before any water is added tothe admixture) with suitable sources of corn including at least of corngrits, corn meal, corn flour and corn starch and which can include ablend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

Another preferred admixture (after any water has been added, i.e. wetadmixture) producing extruded litter pellets having between 1% and 10%carbohydrate polymer binder clumping agent by pellet weight has amoisture content of no more than about 15% by total wet admixture weightand the extruder extrudes the plurality of litter pellets at anextrusion pressure of at least 900 pounds per square inch and atextrusion temperature of at least 140° Celsius. The admixture can bemade of a dry admixture formed of at least 70% by dry admixture weightof at least one cereal grain having a high carbohydrate content of atleast 65% by cereal grain weight and having a high starch content of atleast 60% by cereal grain weight. One such preferred dry admixture hasat least 70% corn by dry admixture weight (before any water is added tothe admixture) with suitable sources of corn including at least of corngrits, corn meal, corn flour and corn starch and which can include ablend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

In a preferred method of making the litter, the extruder extrudespellets having at least 1% of the carbohydrate polymer binder clumpingagent by pellet weight at an extrusion pressure of between 900 poundsper square inch and 1,200 pounds per square inch and at an extrusiontemperature of between 140° Celsius and 165° Celsius. Such a methodproduces litter pellets with at least some of the carbohydrate polymerbinder clumping agent being water soluble. A preferred dry admixture foruse in an extruder under such extruder operating conditions has at least70% corn by dry admixture weight (before any water is added to theadmixture) with suitable sources of corn including at least of corngrits, corn meal, corn flour and corn starch and which can include ablend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

In another preferred method of making the litter, the extruder extrudespellets at an extrusion pressure of between 900 pounds per square inchand 1,200 pounds per square inch and at an extrusion temperature ofbetween 140° Celsius and 165° Celsius producing litter pellets eachhaving at least some carbohydrate polymer binder clumping agent with atleast some of the carbohydrate polymer binder clumping agent being watersoluble and which can be formed of water soluble dextrin. A preferreddry admixture for use in an extruder under such extruder operatingconditions has at least 70% corn by dry admixture weight (before anywater is added to the admixture) with suitable sources of corn includingat least of corn grits, corn meal, corn flour and corn starch and whichcan include a blend or mixture of more than one of corn grits, cornmeal, corn flour and corn starch. Each litter pellet can have asmectite-containing coating that can be formed of bentonite.

Such a preferred method of making the litter, the extruder extrudespellets at an extrusion pressure of between 900 pounds per square inchand 1,200 pounds per square inch and at an extrusion temperature ofbetween 140° Celsius and 165° Celsius causing starch dextrinization tooccur during one of gelatinizing and extruding of the litter pelletsforming at least some dextrin in each extruded litter pellet. Theadmixture can be made of a dry admixture formed of at least 70% by dryadmixture weight of at least one cereal grain having a high carbohydratecontent of at least 65% by cereal grain weight and having a high starchcontent of at least 60% by cereal grain weight. Suitable sources of thecereal grain include at least of corn grits, corn meal, corn flour andcorn starch and which can include a blend or mixture of more than one ofcorn grits, corn meal, corn flour and corn starch. One such method ofmaking litter produces litter pellets each having at least 0.1% dextrinby weight. Another such method produces litter pellets each having atleast 2% dextrin by weight. Still another such method produces litterpellets each having between 0.1% and 5% dextrin by weight. Another suchmethod produces litter pellets each having between 2% and 10% dextrin byweight. Each litter pellet can have a smectite-containing coating thatcan be formed of bentonite.

These and other objects, features and advantages of this invention willbecome apparent from the following detailed description of the inventionand accompanying drawings.

DETAILED DESCRIPTION Litter Pellet Embodiments

The present invention is directed to a method of making a starch basedlitter by extrusion and high starch granules or pellets (hereinafter“pellets”) produced by extrusion that are well suited for use as animallitter. The pellets can be used by themselves as litter or can besubjected to one or more treatment steps after extrusion. The litterpellets are extruded from a high-carbohydrate admixture having at least45% carbohydrates by weight and a relatively low moisture content ofless than 15% by weight producing pellets each having a water-solublecarbohydrate polymer binder disposed about their outer surface that canform at least part of the outer surface of each pellet that reacts towater and urine by dissolving and promoting pellet clumping by lightlyadhesively bonding adjacent pellets together. In one preferredpost-extrusion pellet treatment, a water-absorptive coating thatpreferably includes a smectite, such as bentonite, is applied afterextrusion. Such a treatment can also include the application of apropionate, preferably sodium propionate. Such an admixture preferablyalso is a high starch admixture having at least having at least 45%starch by weight and a relatively low moisture content of less than 12%by weight producing pellets each having a water-soluble carbohydratepolymer binder disposed about their outer surface that can form at leastpart of the outer surface of each pellet that reacts to water and urineby dissolving and promoting pellet clumping by lightly adhesivelybonding adjacent pellets together. In one preferred post-extrusionpellet treatment, a water-absorptive coating that preferably includes asmectite, such as bentonite, is applied after extrusion.

Pellets having such a composition and made using a method in accordancewith the present invention advantageously are self-clumping in a litterbox without the use of an added clumping agent, such as guar gum, as thewater-soluble carbohydrate polymer binder produced from starch in theadmixture during extrusion functions as a clumping agent. The pelletsare advantageously highly water absorptive or hydrophilic as the pelletsrelatively rapidly absorb moisture from fecal matter and urine. Thepellets are also water expulsive in that water rapidly absorbed is inturn wicked to the outer surface of the pellets where it quicklyevaporates. Starch and fiber present in each pellet advantageouslyfunctions as a biological filter adsorbing organic material, such asurea, such that the rapid water evaporation from a clump of pelletsdraws and keeps water away from urea adsorbed by the pellet blocking orhalting the urea cycle while also advantageously preventing bacterial,fungal, yeast and viral growth.

A preferred litter is formed of a plurality of pairs of pellets that aregenerally circular or oval and which can be oblong, e.g., generallycylindrical. Each pellet has an outer surface or skin that is poroushaving a plurality of pairs of pores of different sizes formed therein.Each pellet also has a plurality of pairs of internal voids one or moreof which can be in communication with one or more of the pores. At leasta portion of the skin includes or is formed of a carbohydrate polymerbinder formed during gelatinization by the extruder from which thepellets are extruded with at least some of the binder dissolving orgoing into solution when the pellet is wetted by water, urine or anotherliquid. The water solubilized binder flows with water in betweenadjacent pellets mixing together with water solubilized binder from oneor more adjacent wetted pellets causing the pellets to clump. As waterevaporates, the carbohydrate polymer binder between the adjacent pelletsstrengthens the bond between adjacent pellets more firmly clumping thepellets together enabling the clump of pellets to be removed fromunbound pellets in a litter box, such as by scooping, sifting, strainingor the like.

When used for pet litter, e.g., cat litter, each pellet can be round,e.g., generally oval, or oblong, e.g., generally cylindrical, having awidth or diameter of between two millimeters and ten millimeters and alength no greater than about fifteen millimeters. In one preferredembodiment, a batch of pellets produced in accordance with the presentinvention that is well suited for use as cat litter has at least onehalf of the pellets of the batch having diameters or widths ranging fromabout two millimeters to about four millimeters with lengths rangingfrom about two millimeters to about four millimeters. In anotherpreferred embodiment, a batch of pellets produced in accordance with thepresent invention that is well suited for cat litter has at least onehalf of the pellets of the batch having diameters or widths ranging fromabout four millimeters to about six millimeters with lengths rangingfrom about five millimeters to about ten millimeters. Such sized pelletsare desirable for minimizing a pet or animal using a litter box filledwith such pellets tracking pellets out of the litter box during usage.

Each pellet is of high-starch composition having at least 45% starch byweight and preferably being composed of at least 55% starch by weighthaving an amount by weight of carbohydrate polymer binder producedduring gelatinization by the extruder, including during extrusion fromthe extruder, sufficient to solubilize and self-clump with adjacentpellets upon being wetted with water, urine or another liquid. In apreferred embodiment, each pellet has at least 1% carbohydrate polymerbinder and preferably at least about 2% carbohydrate polymer binder byweight that can be and preferably is relatively uniformly distributedthroughout the pellet with at least some of the carbohydrate polymerbinder disposed at or along the outer surface of the pellet and whichcan form at least a portion of the outer pellet surface. In one suchpreferred embodiment, each pellet has between 2% and 10% carbohydratepolymer binder by weight with at least some of the carbohydrate polymerbinder disposed at or along the outer surface of each pellet enabling itto be dissolved by water, urine or another liquid to form a flowableliquid adhesive that flows from the pellet therealong and in betweenadjacent pellets to bind them and hence clump them together.

In another preferred embodiment, each pellet has at least 3%carbohydrate polymer binder by weight that can be distributed throughoutthe pellet but which has at least some carbohydrate polymer binderdisposed at or along the outer surface of the pellet and which can format least a portion of the outer pellet surface. In one such preferredembodiment, each pellet has between 3% and 10% carbohydrate polymerbinder by weight with at least some of the carbohydrate polymer binderdisposed at or along the outer surface of each pellet enabling it to bedissolved by water, urine or another liquid to form a flowable liquidadhesive that flows from the pellet along the outer pellet surfaceincluding in between adjacent pellets to bind them and hence clump themtogether.

In still another preferred embodiment, each pellet has at least 4%carbohydrate polymer binder by weight that can be distributed throughoutthe pellet but which has at least some carbohydrate polymer binderdisposed at or along the outer surface of the pellet and which can format least a portion of the outer pellet surface. In one such preferredembodiment, each pellet has between 4% and 12% carbohydrate polymerbinder by weight with at least some of the carbohydrate polymer binderdisposed at or along the outer surface of each pellet enabling it to bedissolved by water, urine or another liquid to form a flowable liquidadhesive that flows from the pellet along the outer pellet surfaceincluding in between adjacent pellets to bind them and hence clump themtogether.

In a further preferred embodiment, each pellet has at least 5%carbohydrate polymer binder by weight that can be distributed throughoutthe pellet which has at least some carbohydrate polymer binder disposedat or along the outer surface of the pellet and which can form at leasta portion of the outer pellet surface. In one such preferred embodiment,each pellet has between 5% and 15% carbohydrate polymer binder by weightwith at least some of the carbohydrate polymer binder disposed at oralong the outer surface of each pellet, including forming at least aportion of the outer pellet surface, enabling it to be dissolved bywater, urine or another liquid to form a flowable liquid adhesive thatflows from the pellet along the outer pellet surface including inbetween adjacent pellets to bind them and hence clump them together.

In a preferred pellet embodiment, the carbohydrate polymer binder isformed of starch, which preferably is or includes an amylopectin starchbased carbohydrate polymer binder, at least some of which is disposed ator along the outer pellet surface such that the carbohydrate polymerbinder can form or otherwise define at least a portion of the outerpellet surface. Such a pellet can have such an amylopectin starch basedcarbohydrate polymer binder in any of the minimum weight percentagesand/or weight percentage ranges defined above.

In another preferred pellet embodiment, the carbohydrate polymer bindercan be formed of starch, such as an amylopectin starch basedcarbohydrate polymer binder, but includes dextrin, preferably in theform of yellow dextrin and/or white dextrin, at least some of which isdisposed at or along the outer pellet surface such that the carbohydratepolymer binder can form or otherwise define at least a portion of theouter pellet surface. Such a pellet can have such a dextrin containingcarbohydrate polymer binder in any of the minimum weight percentagesand/or weight percentage ranges defined above.

In still another preferred pellet embodiment, the carbohydrate polymerbinder is formed substantially of dextrin, preferably in the form ofyellow dextrin and/or white dextrin, at least some of which is disposedat or along the outer pellet surface such that the dextrin binder canform or otherwise define at least a portion of the outer pellet surface.Such a pellet can have such dextrin binder in any of the minimum weightpercentages and/or weight percentage ranges discussed below.

Each such dextrin binder containing pellet is of high-starch compositionhaving at least 45% starch by weight and preferably being composed of atleast 55% starch by weight having an amount by weight of dextrinproduced during gelatinization by the extruder, including duringextrusion from the extruder, sufficient to dissolve, flow in betweenadjacent pellets, and self-clump with adjacent pellets upon being wettedwith water, urine or another liquid. In a preferred embodiment, eachpellet has at least 0.1% dextrin and preferably at least about 2%dextrin by weight that can be and preferably is relatively uniformlydistributed throughout the pellet with at least some of the dextrindisposed at or along the outer surface of the pellet forming at least aportion of the outer pellet surface. In one such preferred embodiment,each pellet has between 0.1% and 5% dextrin by weight with at least someof the dextrin disposed at or along the outer surface of each pelletenabling the dextrin to be dissolved by water, urine or another liquidto form a flowable liquid adhesive that flows from the pellet therealongand in between adjacent pellets to bind them and hence clump themtogether thereby producing a self-clumping biodegradable litter mixtureIn another such preferred embodiment, each pellet has between 2% and 10%dextrin by weight with at least some of the dextrin disposed at or alongthe outer surface of each pellet enabling the dextrin to be dissolved bywater, urine or another liquid to form a flowable liquid adhesive thatflows from the pellet therealong and in between adjacent pellets to bindthem and hence clump them together thereby producing a self-clumpingbiodegradable litter mixture. Such a pet or animal litter produced ofextruded litter pellets in accordance with the present invention ispreferably not only biodegradable but also can be toilet flushable.

In another preferred embodiment, each pellet has at least 3% dextrin byweight that can be distributed throughout the pellet but which has atleast some of the dextrin disposed at or along the outer surface of thepellet such that at least a portion of the outer pellet surface can beand preferably is formed of dextrin. In one such preferred embodiment,each pellet has between 3% and 10% dextrin by weight with at least someof the dextrin disposed at or along the outer surface of each pelletenabling it to be dissolved by water, urine or another liquid to form aflowable liquid adhesive that flows from the pellet along the outerpellet surface including in between adjacent pellets to bind them andhence clump them together thereby producing a self-clumpingbiodegradable litter mixture.

In still another preferred embodiment, each pellet has at least 4%dextrin by weight that can be distributed throughout the pellet butwhich has at least some dextrin disposed at or along the outer surfaceof the pellet and which can form at least a portion of the outer pelletsurface. In one such preferred embodiment, each pellet has between 4%and 12% dextrin by weight with at least some of the dextrin disposed ator along the outer surface of each pellet enabling the dextrin to bedissolved by water, urine or another liquid to form a flowable liquidadhesive that flows from the pellet along the outer pellet surfaceincluding in between adjacent pellets to bind them and hence clump themtogether.

In a further preferred embodiment, each pellet has at least 5% dextrinby weight that can be distributed throughout the pellet which has atleast some dextrin disposed at or along the outer surface of the pelletand which can form at least a portion of the outer pellet surface. Inone such preferred embodiment, each pellet has between 5% and 15%dextrin by weight with at least some of the dextrin disposed at or alongthe outer surface of each pellet, including forming at least a portionof the outer pellet surface, enabling the dextrin to be dissolved bywater, urine or another liquid to form a flowable liquid adhesive thatflows from the pellet along the outer pellet surface including inbetween adjacent pellets to bind them and hence clump them together.Such a pellet embodiment produces litter formed of at least a pluralityof pairs, i.e., at least three, of the pellets that is not onlybiodegradable but which also is self-clumping without requiring anyseparate additive to promote clumping.

A plurality of pairs of such pellets produces pet or animal litterhaving a bulk density of no greater than 0.65 grams per cubic centimeter(g/cm³) and preferably no greater than about 0.62 grams per cubiccentimeter (g/cm³) which has a bulk density of at least 40% less thanconventional clay-based (e.g., bentonite containing) cat litters havinga bulk density of no less than 1 gram per cubic centimeter (g/cm³) thatis at least 50% lighter in weight and preferably at least 60% lighter inweight for a given volume as compared to conventional clay-based (e.g.,bentonite containing) cat litters making containers of litter producedof coated pellets in accordance with the present invention much easierfor a person to carry as compared to a container of the same size filledwith conventional clay-based litter. Pet or animal litter composed ofsuch pellets (whether the pellets are coated or uncoated) have pelletswhen uncoated with a weight per liter of at least 200 grams per literand preferably at least 250 grams per liter helping to produce agranular pelletized litter formed of pellets (whether coated oruncoated) having a desired pellet density and consistency that not onlyminimizes tracking but which also absorbs liquid and clumps similar toand preferably better than conventional clay-based (e.g., bentonitecontaining) cat litters. In another preferred pet or litter formed ofsuch pellets (whether coated or uncoated), the uncoated pellets have aweight per liter of at least 275 grams per liter.

Litter Pellet Coating and Coating Methods

Each pellet can be coated with a coating covering the outer surface ofeach pellet with the coating formulated to enhance pellet performanceincluding by increasing the ability of each pellet to absorb orfacilitate absorption of water, urine, or another liquid as well as totreat material, including fecal matter, urine, water or another liquidthat comes into pellet contact. In a preferred embodiment, any one ofthe above described pellet embodiments are coated with a coating thatincludes a smectite. One preferred smectite is a type of clay thatpreferably is a bentonite, e.g. preferably sodium bentonite. Such acoating can also include sodium bicarbonate, e.g. baking soda, azeolite, and a scent if desired. Such a coating can also include silica,such as crystalline silica, as well as calcium carbonate.

In a preferred coated pellet embodiment, any one of the plurality ofpairs of uncoated pellets embodiments can be coated with such a coatingafter extrusion. In one preferred implementation of a method of makingcoated litter in accordance with the present invention, the pellets arecoated relatively shortly after extrusion and before any drying of thepellets is done. In another preferred implementation of a method ofmaking coated litter in accordance with the present invention, thepellets are coated more than an hour after extrusion as the pellets canbe coated after the pellets are dried including at a location remotefrom where the pellets where extruded.

One preferred coating formulation includes at least 65% by coatingweight of smectite that preferably is sodium bentonite that is ground orcrushed into a powder having an average mesh size of about 20 mesh orgreater (i.e., 30 mesh, 50 mesh, or finer mesh), preferably having amesh size of 50 mesh or greater (i.e., 70 mesh, 100 mesh, or finermesh), and which has an average particle size no greater than about 400microns. Such a powdered coating includes no more than 10% by coatingweight of either sodium bicarbonate or calcium bicarbonate. Where thepowdered coating includes zeolite, the powdered coating includes no morethan 10% by coating weight of zeolite. Such a powdered coatingformulation can contain silica, e.g., crystalline silica, but not morethan about 8% by coating weight. Where the powdered coating includes ascent or a fragrance, such a powdered coating includes no more than 3%and preferably less than about 1% by coating weight of a scent orfragrance.

One preferred coating formulation includes at least 80% by coatingweight of smectite that preferably is sodium bentonite that is ground orcrushed into a powder having an average mesh size of about 50 mesh orgreater and which has an average particle size no greater than about 400microns. Such a powdered coating includes no more than 10% by coatingweight of either sodium bicarbonate or calcium bicarbonate. Where thepowdered coating includes zeolite, the powdered coating includes no morethan 8% by coating weight of zeolite. Such a powdered coatingformulation can contain silica, e.g., crystalline silica, but not morethan about 8% by coating weight. Where the powdered coating includes ascent or a fragrance, such a powdered coating includes no more than 2%and preferably less than about 1% by coating weight of a scent orfragrance. Such a coating is not limited to just these constituents asother constituents can be used. The amount of coating applied to eachpellet preferably amounts to no more than 5% pellet weight once thecoating has dried or cured.

Such a coating formulation can be applied as a powder to pellets thatcan be and preferably are uncoated, mixed with a liquid, such as water,which is sprayed on the pellets, or otherwise applied to uncoatedpellets in a manner that coats them. Such a coating formulation can beapplied using an agglomerator, such as a commercially availableagglomerator, and/or using a coating tumbler, such as a commerciallyavailable coating tumbler or the like.

In one preferred method of applying such a coating formulation,preferably one of the above-described coating formulations, the coatingformulation is applied in powdered form onto uncoated pellets in acommercial agglomerator or a commercial coating tumbler that rotates,tumbles, vibrates and/or otherwise agitates pellets therein within ashort enough period of time after extrusion of the pellets that theouter surface of the pellets are still sticky or tacky facilitatingadherence of the powdered coating formulation to each pellet. In onesuch preferred method of applying the coating, the coating formulationis applied onto uncoated pellets within an hour of being extruded andwhile at least some of the carbohydrate polymer binder on or of theouter surface of each pellet is still sticky or tacky thereby using theclump facilitating binder in each pellet produced during extrusion tofacilitate adherence of the powdered coating formulation to each pellet.In another such preferred method of applying the coating, the coatingformulation is applied onto uncoated pellets within a half hour of beingextruded and while at least some of the carbohydrate polymer binder onor of the outer surface of each pellet is still sticky or tacky therebyusing the clump facilitating binder in each pellet produced duringextrusion to facilitate adherence of the powdered coating formulation toeach pellet. In still another such preferred method of applying thecoating, the coating formulation is applied onto uncoated pellets withinfifteen minutes of being extruded and while at least some of thecarbohydrate polymer binder on or of the outer surface of each pellet isstill sticky or tacky thereby using the clump facilitating binder ineach pellet produced during extrusion to facilitate adherence of thepowdered coating formulation to each pellet.

In one preferred method of applying such a coating formulation, thecoating formulation is applied using a liquid, such as water, and apressurized gas, such as pressurized air, which not only helps vaporizeor mist the coating formulation containing liquid but also helps agitateor move around the pellets in a drum, container or enclosure which arebeing coated. In such a preferred method of applying a coatingformulation onto pellets that can be uncoated, such as right after beingextruded, a ground or powdered coating formulation, such as one of theabove-described formulations, is mixed with liquid, e.g., water, whichcan be sprayed from a nozzle together with compressed air into anenclosure, such as a drum or other container, which contains pelletshelping to agitate the pellets and coat the pellets with a minimum ofdisturbance or damage to the pellets during coating. The drum orcontainer in which the pellets are disposed during such a coating steppreferably is rotated, vibrated or otherwise agitated to help facilitatecoating each pellet.

In a preferred coating arrangement, the liquid with which the ground orpowdered coating formulation is mixed provides a liquid carrier for theground or powdered coating formulation that can and preferably doesinclude one or more antimicrobial agents, antifungal agents, and/oranti-yeast agents in the liquid that are at least partially absorbedinto each pellet to treat each pellet during the coating step and/or atleast form part of the outer coating of each pellet thereby treating thecoating and/or pellet during the coating step. Such a liquid coatingformulation carrier can include one or more inhibitors in the liquidthat can be one or more urine breakdown inhibitors(s), such as one ormore urease inhibitor(s) and/or one or more de-nitrification inhibitors.Such a liquid coating formulation carrier can also include a citrate,such as sodium citrate, and/or an acid, such as citric acid, and/orpropionic or propanoic acid that can be at least partially absorbed byeach pellet during the coating step treating each pellet and/or form atleast part of the coating that covers each pellet during the coatingstep. Such treatments added to the liquid that serves as a carrier inwhich ground or powdered coating formulation is mixed and applied, e.g.,sprayed, onto the pellets during the coating step treats each pelletand/or the coating applied to each pellet during the coating step in amanner that inhibits odor, inhibits bacterial growth, inhibits fungalgrowth, inhibits viral growth, and/or inhibits yeast growth.

If desired, one or more of these treatments can be applied in a stepseparate from that of the coating step where each pellet is coated witha ground or powdered coating formulation in accordance with thatdiscussed above. One or more of these treatments can be applied in atreatment step performed before the coating step where it is desired forat least some of the treatment(s) applied to the pellets to be at leastpartially absorbed into each pellet or coat the outer surface of eachpellet before coating each pellet with the powdered or ground coatingformulation. It is also contemplated performing the coating step beforeperforming a treatment step such as where it is also desired to treatthe coating. Finally, a method of making litter pellets in accordancewith the present invention contemplates performing one or more treatmentsteps before performing one or more coating steps further contemplatingperforming one or more treatment steps after the coating step(s) is/areperformed.

One example of a suitable urine breakdown inhibitor treatment that canbe applied during a treatment and/or coating step is Dicyandiamide(DCD), which is also known as Cyanoguanidine, 1-Cyanoguanidine, or2-Cyanoguanidine, can be included as an additive, e.g. additive 40, 42,44, and/or 46, or as a coating 48. If desired, a member of a cyanamidederivate, such as Guanidine hydrochloride, Chlorohexidine, Biguanide,3-Amino-1,2,4-trazole, Aminoguanidine, Tetramethyl guanidine,Benzoguanamine, 1-o-Tolylbiguanide, Cyanodithioimidocarbonic acid,2-Aminopyrimidine, Dodecyl guanidine, Guanidine, Disodiumcyanodithioimidocarbonate, Cyanamide, Butylbiguanide, Guanidiniumsulfate, 2-Amino-4-methoxy-6-methyl-1,3,5-trazine, Pimagedinehydrochloride, Phenylguanidine, Guanylthiourea, Cyprex, O-Methylisourea,Aminoguanidine bicarbonate, 3-Amino-5-carboxy-1,2,4-triazole,Chlorhexidine hydrochloride, 5-Amono-1H-tetrazole, 1-o-Tolylbiguanidemonohydrochloride, N-Cyanoacetoimidate, Dodecylguanidine hydrochloride,Carbazamidine hydrochloride, 3-Amino-5-mercapto-1,2,4-triazole,Cyanoimidocarbonic acid dimethylester, 2-Amino-4,6-dimethoxy-pyrimidine,Guanidine sulfamate, Bis(2-methylisouronium)sulfate, and/or2-Methylisouronium acetate, can be used with or instead of DCD. DCD orone of the aforementioned equivalents can function as a urease inhibitorthat inhibits the action of the urease enzyme to prevent urease frombreaking down urea in urine absorbed by pellets of litter containing DCD(and/or an equivalent). It should be noted that DCD also is ade-nitrification inhibitor that prevents lighter vapor pressureammoniated products from being released from the degradation orbreakdown of urea byproducts and/or the degradation or breakdown ofother components in urine deposited in pellets of the litter containingsuch an inhibitor.

Another example of a suitable urine breakdown inhibitor that can also beapplied during a treatment and/or coating step is hydroquinone (HQ) asit is a urease inhibitor that inhibits the action of the urease enzymein breaking down urea in urine. Hydroquinone is also known asbenzene-1,4-diol or quinol. As a result of inhibiting the action ofurease, HQ prevents the breakdown of urea in urine in litter composed ofpellets in accordance with the present invention by preventing theformation of lighter vapor pressure ammoniated product from exitingpellets that have absorbed animal urine. If desired, other hydroquinonesor hydroquinone equivalents can be used with or instead of HQ. It iscontemplated that HQ (or another hydroquinone) used with DCD. One ormore hydroquinones can be included in a treatment/coating wettingmixture that includes DCD and/or one or more derivatives of DCD,including one or more of those listed in the preceding paragraph.

A still further example of a suitable urine breakdown inhibitortreatment that can also be applied during a treatment and/or coatingstep is N-(n-butyl) thiophosphoric triamide (NBPT) as it also is aurease inhibitor that inhibits the action of the urease enzyme inbreaking down urea in urine. If desired, one or more NBPT equivalentscan be used with or instead of NBPT. It is contemplated that HQ can bepart of a litter mixture that also includes DCD and/or anotherhydroquinone. In another litter mixture, NBPT (or an equivalent(s)) canbe applied to treat pellets of a litter mixture that also includes DCDand/or one or more derivatives of DCD, including one or more of thoselisted above. In a still further litter mixture, NBPT (or anequivalent(s)) can be applied to treat pellets of a litter mixture thatalso includes DCD and/or one or more derivatives of DCD along with oneor more hydroquinones.

Another treatment that can be applied is a propionate, preferably sodiumpropionate, which can be added as a pellet stabilizer that can stabilizeand/or prevent re-crystallization and/or retrogradation of starch ineach pellet.

Where such a coating formulation is applied to the pellets, theapplication of the coating formulation is done in such a manner, such asusing an agglomerator, a coating tumbler or the like, to coat eachpellet with a coating having a thickness of at least 50 microns. In apreferred method of coating the pellets, an agglomerator or coatingtumbler is used to apply a coating formulation, such as one of theabove-described coating formulations, to coat each pellet with a coatinghaving a thickness of at least 50 microns that can vary between 50microns (e.g., 0.05 millimeter) and about 1000 microns (e.g., 1millimeter) that substantially completely covers substantially theentire outer surface of each pellet being coated. In another preferredmethod of coating the pellets, an agglomerator or coating tumbler isused to apply a coating formulation, such as one of the above-describedcoating formulations, to coat each pellet with a coating having athickness of at least 100 microns that can vary between 100 microns(e.g., 0.1 millimeter) and about 1000 microns (e.g., 1 millimeter) thatsubstantially completely covers substantially the entire outer surfaceof each pellet being coated.

When the coating dries or sets after the coating step has beenperformed, the coating helps strengthen each pellet helping to impart toeach coated pellet a crush strength that is at least 75% that ofconventional bentonite clay based cat litters having a bulk density atleast 80% greater than coated pellets produced in accordance with thepresent invention. In a preferred coated pellet embodiment, such acoating imparts a crush strength that is at least 85% that ofconventional bentonite clay based cat litters having a bulk densitynearly twice as great and, in at least some instances more than twice asgreat, as the bulk density of coated pellets produced in accordance withthe present invention.

In a preferred coated pellet embodiment, a plurality of pairs of coatedpellets coated with a bentonite containing coating, such as describedabove, having a coating thickness between 0.1 millimeters and 1millimeters produces coated pellets having a bulk density of no greaterthan 0.7 grams per cubic centimeter (g/cm³) and preferably no greaterthan about 0.65 grams per cubic centimeter (g/cm³) which has a bulkdensity of at least 35% less than conventional clay-based (e.g.,bentonite containing) cat litters having a bulk density of no lower than1 gram per cubic centimeter (g/cm³). One preferred coated pelletembodiment is coated with such a bentonite containing coating has a bulkdensity of no greater than 0.65 grams per cubic centimeter (g/cm³) andpreferably no greater than about 0.62 grams per cubic centimeter (g/cm³)which has a bulk density of at least 40% less than conventionalclay-based (e.g., bentonite based) cat litters having a bulk density ofabout 1.1 grams per cubic centimeter (g/cm³). Litters produced with suchcoated pellets are therefore at least 40% lighter in weight andpreferably at least about 50% lighter in weight for a given volume ascompared to conventional clay-based (e.g., bentonite containing) catlitters making containers of litter produced of coated pellets inaccordance with the present invention much easier for a person to carryas compared to a container of the same size filled with conventionalclay-based litter.

When the coating dries or sets after the coating step has beenperformed, the coating substantially completely covers substantially theentire outer surface of each pellet being coated helping to encapsulateeach pellet helping to produce a coated pellet having desirable urineand fecal matter absorption and clumping characteristics. Such a coatingsubstantially encapsulating each pellet forms a hard shell that appearsand feels to an animal, e.g., cat, stepping on and/or in litter formedof a plurality of the coated pellets as if the animal were stepping onand/or in conventional clay-based cat litter.

When the coating dries or sets after the coating step has beenperformed, the coating substantially completely covers substantially theentire outer surface of each pellet being coated helping to encapsulateeach pellet helping to produce a coated pellet having desirable urineand fecal matter absorption and clumping characteristics. Such a coatingsubstantially encapsulating each pellet also helps retain anytreatment(s) applied to the pellets or at least slow the rate at whichsuch treatments may possibly evaporate, degrade or otherwise reduce ineffectiveness. Such a coating substantially encapsulating each pelletalso allows greater concentrations of such treatments to be appliedincluding concentrations that normally would be considered toxic toanimals because the coating serves as a barrier preventing an animal,e.g., cat using the litter from coming into contact with such higherconcentrations.

Such a coating substantially encapsulating each pellet also allowstreatments normally considered toxic to animals to be applied becausethe coating serves as a barrier preventing an animal, e.g., cat usingthe litter from coming into contact with such potentially toxictreatments. Examples of such treatments that are potentially toxic thatcan be applied to the pellets in a treatment step performed before thecoating step include phenols, glycols, triclosan, certain chlorides,e.g., benzyl chloride, hypochlorite or sodium hypochlorite, e.g.chlorine, ethylene oxide, methyl bromide, peroxycetic acid, pyrethinsand pyrethroids, organophosphates, carbamates, organochlorides,anti-parasitic treatments, and/or other potentially toxic chemicals andcompounds. The coating subsequently applied to each treated pelletadvantageously helps prevent the potentially toxic chemical(s) andcompound(s) in each treated pellet from coming into contact with theanimal while the animal is in contact with litter formed of a pluralityof pairs of the coated pellets including during urination and defecationby the animal in the litter. By such a coating enabling safe use of sucha potentially toxic treatment or treatments applied to pellets producedin accordance with the present invention advantageously provides betterinhibition of bacterial growth, better inhibition of fungal growth,and/or better inhibition of yeast growth thereby helping to providebetter odor control.

A preferred anti-parasitic treatment capable of inhibiting and/orkilling toxoplasma gondii protozoa is comprised of artemisinin in aground, powdered, or other comminuted form and/or that can besolubilized or dissolved in a liquid, preferably water, to treat eachpellet before and/or during pellet coating producing a treated pellethaving at least 0.25% by pellet weight and preferably between 0.25% and5% by pellet weight. Another preferred anti-parasitic treatment iscetylpyridinium chloride applied in a concentration or amount of atleast 0.25% by pellet weight and preferably between 0.25% and 3% bypellet weight. Still another preferred anti-parasitic treatment isnatural or synthetic pyrethroids in a concentration of at least 0.25% bypellet weight and preferably between 0.25% and 5% by pellet weight.Other anti-parasitic treatments that inhibit and/or kill toxoplasmagondii protozoa include cyhalothrin, bifenthrin, carbaryl or anothercarbamate, Imidacloprid or another neonicotinoid, fipronil or anotherGABA receptor pesticide, permethrin, diazinon, dichorvos, DDT(dichlorodiphenyltrichloroethane) or another organophosphateinsecticide, and/or chlorfenapyr or another pro-insecticide in an amountsufficient to inhibit and preferably kill toxoplasma gondii protozoa infeline fecal material deposited in litter formed of pellets formulatedand produced in accordance with the present invention. One or more ofsuch anti-parasitic treatments can be added to the admixture duringmaking of the admixture, added to water added to the admixture, added tothe extruder during gelatinization and/or extrusion, applied to thepellets after extrusion, included as part of any pellet coating mixture,and/or applied before, during and/or after coating the pellets.

Litter Pellet Making Methods Introduction

A preferred method of making a pellet in accordance with the presentinvention does so using a single screw or twin screw extruder thatgelatinizes a starch-containing admixture having a sufficient amount andtype(s) of starch that produces a carbohydrate polymer binder anddistributes at least some of the binder in and along an outer surface ofa pellet extruded from the extruder. In a preferred implementation ofthe method, the starch-containing admixture possesses relatively lowmoisture and has a sufficient amount of starch of a desiredamylose:amylopectin ratio or within a desired amylose:amylopectin rangethat causes starch dextrinization to occur during extrusion using asingle screw or twin screw extruder producing a plurality of pairs ofextruded pellets that each have a sufficient amount of dextrin thatenables the pellets to self-clump when wetted by liquid.

Admixture Formulation

A preferred starch-containing admixture is formed substantially of oneor more high carbohydrate, high starch cereal grains to produce anadmixture having a carbohydrate content of at least 60% by weight and astarch content of at least 45% by weight when the weight of any waterpresent in each cereal grain used in the admixture is discounted oreliminated from consideration. Another preferred starch-containingadmixture formed substantially of one or more high carbohydrate, highstarch cereal grains has a carbohydrate content of at least 65% byweight and a starch content of at least 55% by weight when the weight ofany water present in each cereal grain of the admixture is discounted oreliminated from consideration.

Suitable high carbohydrate, high starch cereal grains include one ormore of corn or maize, rice, wheat, triticale, amaranth, and/or sorghum.Each cereal grain used to make an admixture in accordance with thepresent invention preferably is comminuted, e.g., ground, in a mannerthat produces reduced size cereal grain particles in the form of grits,meal, starch, or flour that is mixed in an admixture mixing step to makethe admixture. Each cereal grain used to make such an admixture can becomminuted in a separate comminuting step but preferably is purchased ina form where each cereal grain used to make the admixture already hasbeen comminuted.

Examples of suitable commercially available comminuted highcarbohydrate, high starch grain cereals include corn grits, cornmeal,corn starch, corn flour, rice grits, rice meal, rice starch, rice flour,wheat grits, wheat meal, wheat starch, wheat flour, triticale grits,triticale meal, triticale starch, triticale flour, amaranth grits,amaranth meal, amaranth starch, amaranth flour, sorghum grits, sorghummeal, sorghum starch and/or sorghum flour. Such suitable highcarbohydrate, high starch grain cereals can be whole or degermed. Suchsuitable high carbohydrate, high starch grain cereals can also be starchmodified, such as chemically modified, such as by chemicallycross-linking in a manner producing chemically cross-linked starches.

In one preferred admixture, each of the one or more suitable highcarbohydrate high starch containing cereal grains used to form anadmixture in accordance with the present invention preferably has starchwith an amylose content of no more than 50% of the starch present ineach one of the one or more high carbohydrate, high starch grain cerealsused to make the admixture. In another preferred admixture, the starchof each one of the one or more high carbohydrate high starch containingcereal grains used to form an admixture in accordance with the presentinvention preferably has an amylose:amylopectin ratio of between 10:90and 45:55. In still another preferred admixture, the starch of the oneor more high carbohydrate high starch containing cereal grains used tomake the admixture has an amylose:amylopectin ratio of between 15:85 and40:60. In a further preferred admixture, the starch of each one of theone or more high carbohydrate high starch containing cereal grains usedto make the admixture has an amylose:amylopectin ratio of between 20:80and 35:65.

In one preferred admixture, the starch of each of the one or moresuitable high carbohydrate high starch containing cereal grains used toform an admixture in accordance with the present invention includes bothamylose and amylopectin where the amylopectin has a weight averagemolecular weight ranging between 25 million g/mol. and 650 milliong/mol. In such a preferred admixture, the starch of each of the one ormore suitable high carbohydrate high starch containing cereal grainsused to form an admixture in accordance with the present inventionpreferably gels during gelatinization substantially without producingany paste during gelatinization. In such a preferred admixture, thestarch of each of the one or more suitable high carbohydrate high starchcontaining cereal grains used to form an admixture in accordance withthe present invention has a short gel texture. In such a preferredadmixture, the starch of each of the one or more suitable highcarbohydrate high starch containing cereal grains used to form anadmixture in accordance with the present invention has a starch grainsize or diameter of no greater than 40 microns. In such a preferredadmixture, the starch of each of the one or more suitable highcarbohydrate high starch containing cereal grains used to form anadmixture in accordance with the present invention is unimodal made upof spherical or polyhedral shaped starch granules without havingsubstantially any lenticular shaped starch granules.

One preferred starch-containing admixture is formed of a mixture of oneof more high carbohydrate, high starch cereal grains making up between50% and 80% of dry admixture weight before adding any water to theadmixture with the mixture of one or more cereal grains having acarbohydrate content of at least 60% by cereal grain mixture weight anda starch content of at least 50% by cereal grain mixture weight. Anotherpreferred starch-containing admixture is formed of a mixture of one ofmore high carbohydrate, high starch cereal grains making up between 50%and 80% by weight (before the addition of any water to the admixture)with the mixture of one or more cereal grains having a carbohydratecontent of at least 65% of cereal grain mixture weight and a starchcontent of at least 60% of cereal grain mixture weight. A furtherpreferred starch-containing admixture is formed of a mixture of one ofmore high carbohydrate, high starch cereal grains making up between 50%and 80% by (before the addition of any water to the admixture) with themixture of one or more cereal grains having a carbohydrate content of atleast 70% of cereal grain mixture weight and a starch content of atleast 65% of cereal grain mixture weight.

Where less than the entire admixture is made of high carbohydrate, highstarch cereal grains, a cellulosic material in an amount of at least 5%and no greater than 50% of the total admixture weight (before theaddition of any water to the admixture) can be added to the admixture toprovide the remainder of the admixture with the cellulosic materialbeing added in an amount sufficient to help not only facilitate liquidabsorption during pet or animal litter use but also to help generallyretain pellet structure in a manner that helps water soluble binderclumping of adjacent pellets in a litter box. Suitable cellulosicmaterial(s) include one or more of a wood fiber, hay, preferably alfalfahay oat hay or another type of hay, beet fiber, preferably beet pulp, oranother cellulosic material. Where less than the entire admixture ismade of cereal grains, the remainder of the admixture can include sodiumchloride in an amount of between about 0% and about 5% of the admixtureweight (before the addition of any water to the admixture) can be addedto the admixture to help produce or otherwise help induce formation ofcarbohydrate polymer binder during gelatinization and/or extrusionpreferably by helping to produce or help induce dextrin formation ordextrinization. If desired, glycerol monostearate (GMS) in an amount ofno more than about 1% and preferably between 0% and 0.2% by totaladmixture weight (before the addition of any water to the admixture) canalso be added to the admixture to help produce a desired gelatinizedadmixture viscosity during extrusion that helps maintain generallyconstant extrusion temperatures and pressures during extrusion and whichalso can function as a surfactant that can help with the plating orcoating of the pellets using any one of the coating formulationsdiscussed above.

The balance or remainder of such an admixture formulation can alsoinclude one or more of the following additional constituents: fillers,odor inhibitors, scents, fragrances, adsorbents, bacteriostats,antiviral additives, antifungal additives, anti-yeast additives, urea orurease inhibitors, or the like as well as incidental matter and/orincidental impurities. For any one of the admixture formulationsdisclosed in the preceding two paragraphs, the balance or remainder ofthe admixture formulation can also include one or more of the followingadditional constituents in an amount no greater than about 5% each oftotal admixture weight (before the addition of any water to theadmixture) of the following: fillers, odor inhibitors, scents,fragrances, adsorbents, bacteriostats, antiviral additives, antifungaladditives, anti-yeast additives, urea or urease inhibitors, or the likeas well as incidental matter and/or incidental impurities.

Another preferred starch-containing admixture is formed of a mixture ofone of more high carbohydrate, high starch cereal grains making upbetween 60% and 90% by weight of the total admixture (before theaddition of any water to the admixture) with the mixture of the one ormore high carbohydrate, high starch cereal grains having a carbohydratecontent of at least 60% by cereal grain mixture weight and a starchcontent of at least 50% by cereal grain mixture weight. Still anotherpreferred starch-containing admixture (before the addition of any waterto the admixture) is formed of a mixture of one of more highcarbohydrate, high starch cereal grains making up between 60% and 90% byweight of the total admixture with the mixture of the one or more highcarbohydrate, high starch cereal grains having a carbohydrate content ofat least 65% by cereal grain mixture weight and a starch content of atleast 60% by cereal grain mixture weight. A further preferredstarch-containing admixture is formed of a mixture of one of more highcarbohydrate, high starch cereal grains making up between 60% and 90% byweight (before adding any water to the admixture) with the mixture ofone or more cereal grains having a carbohydrate content of at least 70%of cereal grain mixture weight and a starch content of at least 65% ofcereal grain mixture weight.

Where less than the entire admixture of the preceding paragraph is madeof high carbohydrate, high starch cereal grains, the remainder of theadmixture can include a cellulosic material in an amount of at least 5%and no greater than 40% of admixture weight (before the addition of anywater to the admixture). The remainder of the admixture can furtherinclude sodium chloride in an amount of between 0.1% and 5% of theadmixture weight (before the addition of any water to the admixture) canbe added to the admixture. If desired, glycerol monostearate in anamount of no more than about 0.2% by total admixture weight (before theaddition of any water to the admixture) can also be added to theadmixture.

The balance or remainder of such an admixture formulation can alsoinclude one or more of the following additional constituents: fillers,odor inhibitors, scents, fragrances, adsorbents, bacteriostats,antiviral additives, antifungal additives, anti-yeast additives, urea orurease inhibitors, and/or the like as well as incidental matter and/orincidental impurities. For any one of the admixture formulationsdisclosed in the preceding two paragraphs, the balance or remainder ofthe admixture formulation can also include one or more of the followingadditional constituents in an amount no greater than about 5% each oftotal admixture weight (before the addition of any water to theadmixture) of the following: fillers, odor inhibitors, scents,fragrances, adsorbents, bacteriostats, antiviral additives, antifungaladditives, anti-yeast additives, urea or urease inhibitors, and/or thelike as well as incidental matter and/or incidental impurities.

Another preferred starch-containing admixture is formed of a mixture ofone of more of high carbohydrate, high starch cereal grains that make upbetween 80% and 95% by weight of the total admixture (before theaddition of any water to the admixture) with the mixture of one or morecereal grains having a carbohydrate content of at least 60% by cerealgrain mixture weight and a starch content of at least 45% by cerealgrain mixture weight. Still another preferred starch-containingadmixture is formed of a mixture of one of more cereal grains that makeup between 80% and 95% by weight of the total admixture (before theaddition of any water to the admixture) with the mixture of one or morecereal grains having a carbohydrate content of at least 65% by cerealmixture weight and a starch content of at least 55% by cereal grainmixture weight. A further preferred starch-containing admixture isformed of a mixture of one of more cereal grains that make up between80% and 95% by weight of the total admixture (before the addition of anywater to the admixture) with the mixture of one or more cereal grainshaving a carbohydrate content of at least 70% by cereal mixture weightand a starch content of at least 60% by cereal grain mixture weight.

Where less than the entire admixture of the preceding paragraph is madeof high carbohydrate, high starch cereal grains, the remainder of theadmixture can include a cellulosic material in an amount of at least 2%and no greater than 20% of admixture weight (before the addition of anywater to the admixture). The remainder of the admixture can furtherinclude sodium chloride in an amount of between 0.1% and 5% of theadmixture weight (before adding any water) added to the admixture. Ifdesired, glycerol monostearate in an amount of no more than about 0.2%of total admixture weight (before adding any water) can also be added.

The balance or remainder of such an admixture formulation can alsoinclude one or more of the following additional constituents: fillers,odor inhibitors, scents, fragrances, adsorbents, bacteriostats,antiviral additives, antifungal additives, anti-yeast additives, urea orurease inhibitors, and/or the like as well as incidental matter and/orincidental impurities. For any one of the admixture formulationsdisclosed in the preceding two paragraphs, the balance or remainder ofthe admixture formulation can also include one or more of the followingadditional constituents in an amount no greater than about 5% each oftotal admixture weight (before the addition of any water to theadmixture) of the following: fillers, odor inhibitors, scents,fragrances, adsorbents, bacteriostats, antiviral additives, antifungaladditives, anti-yeast additives, urea or urease inhibitors, and/or thelike as well as incidental matter and/or incidental impurities.

Another preferred starch-containing admixture is formed of a mixture ofone of more of high carbohydrate, high starch cereal grains that make upbetween 80% and 99% (≈100%) by weight of the total admixture (before theaddition of any water to the admixture) with the mixture of one or morecereal grains having a carbohydrate content of at least 60% by cerealgrain mixture weight and a starch content of at least 45% by cerealgrain mixture weight. Still another preferred starch-containingadmixture is formed of a mixture of one of more cereal grains that makeup between 80% and 99% (≈100%) by weight of the total admixture (beforethe addition of any water to the admixture) with the mixture of one ormore cereal grains having a carbohydrate content of at least 65% bycereal mixture weight and a starch content of at least 55% by cerealgrain mixture weight. A further preferred starch-containing admixture isformed of a mixture of one of more cereal grains that make up between80% and 99% (≈100%) by weight of the total admixture (before theaddition of any water to the admixture) with the mixture of one or morecereal grains having a carbohydrate content of at least 70% by cerealmixture weight and a starch content of at least 60% by cereal grainmixture weight.

Where less than the entire admixture of the preceding paragraph is madeof high carbohydrate, high starch cereal grains, the remainder of theadmixture can include a cellulosic material containing at least 20%cellulose by total weight of the cellulose material in an amount of atleast 2% and no greater than 20% of admixture weight (before theaddition of any water to the admixture). In at least one preferredadmixture, the dry admixture has no more than about 5% of a cellulosematerial containing at least 20% cellulose by total weight of thecellulose material. In another preferred admixture, the dry admixturecontains no cellulosic material. The remainder of the admixture canfurther include sodium chloride in an amount of between 0.1% and 5% ofthe admixture weight (before adding any water) added to the admixture.If desired, glycerol monostearate in an amount of no more than about0.2% of total admixture weight (before adding any water) can also beadded.

The balance or remainder of such an admixture formulation can alsoinclude one or more of the following additional constituents: fillers,odor inhibitors, scents, fragrances, adsorbents, bacteriostats,antiviral additives, antifungal additives, anti-yeast additives, urea orurease inhibitors, and/or the like as well as incidental matter and/orincidental impurities. For any one of the admixture formulationsdisclosed in the preceding two paragraphs, the balance or remainder ofthe admixture formulation can also include one or more of the followingadditional constituents in an amount no greater than about 5% each oftotal admixture weight (before the addition of any water to theadmixture) of the following: fillers, odor inhibitors, scents,fragrances, adsorbents, bacteriostats, antiviral additives, antifungaladditives, anti-yeast additives, urea or urease inhibitors, and/or thelike as well as incidental matter and/or incidental impurities.

Another preferred starch-containing admixture is formed of a mixture ofone of more cereal grains that make up between 90% and 99% (≈100%) byweight of the total admixture (before the addition of any water to theadmixture) with the mixture of one or more cereal grains having acarbohydrate content of at least 60% by cereal grain mixture weight anda starch content of at least 45% by cereal grain mixture weight. Stillanother preferred starch-containing admixture is formed of a mixture ofone of more cereal grains that make up between 90% and 99% by weight ofthe total admixture (before the addition of any water to the admixture)with the mixture of one or more cereal grains having a carbohydratecontent of at least 65% by cereal mixture weight and a starch content ofat least 55% by cereal grain mixture weight. A further preferredstarch-containing admixture is formed of a mixture of one of more cerealgrains that make up between 90% and 99% by weight of the total admixture(before the addition of any water to the admixture) with the mixture ofone or more cereal grains having a carbohydrate content of at least 70%by cereal mixture weight and a starch content of at least 60% by cerealgrain mixture weight.

Where less than the entire admixture of the preceding paragraph is madeof high carbohydrate, high starch cereal grains, the remainder of theadmixture can include a cellulosic material in an amount between 0% and10% admixture weight (before the addition of any water to theadmixture). The remainder of the admixture can further include sodiumchloride in an amount of between 0% and 1% of the admixture weight(before the addition of any water to the admixture) added to theadmixture. If desired, glycol monostearate in an amount of between 0%and 0.2% of total admixture weight (before the addition of any water tothe admixture) can also be added.

The balance or remainder of such an admixture formulation can alsoinclude one or more of the following additional constituents: fillers,odor inhibitors, scents, fragrances, adsorbents, bacteriostats,antiviral additives, antifungal additives, anti-yeast additives, urea orurease inhibitors, and/or the like as well as incidental matter and/orincidental impurities. For any one of the admixture formulationsdisclosed in the preceding two paragraphs, the balance or remainder ofthe admixture formulation can also include one or more of the followingadditional constituents in an amount no greater than about 5% each oftotal admixture weight (before the addition of any water to theadmixture) of the following: fillers, odor inhibitors, scents,fragrances, adsorbents, bacteriostats, antiviral additives, antifungaladditives, anti-yeast additives, urea or urease inhibitors, and/or thelike as well as incidental matter and/or incidental impurities.

An admixture formulated in accordance with the present invention,including having any of the above-disclosed admixture formulations, hasa moisture or water content of at least 7% by weight and no more than18% water by total wet admixture weight when being processed by theextruder during gelatinization and/or extrusion of the admixture. Inanother preferred admixture, the admixture has a moisture or watercontent of between about 8% and about 17% water by weight. In anotherpreferred admixture, the admixture has a moisture or water content ofbetween about 8.5% and about 16% water by weight. In still anotherpreferred admixture, the admixture has a moisture or water content ofbetween 9% and 15% by admixture weight.

Where the admixture has too much water, a water reduction step can beperformed prior to or during mixing or gelatinization, such as by dryingthe admixture, to bring the total moisture or water content to a levelwithin a corresponding desired one of the 7%-18%, 8%-17%, 8.5%-16% and9%-15% water content ranges disclosed above. Where a drying step isperformed, it can be performed as a separate step using a commercialdryer, an oven, using a desiccant, or the like.

Another admixture formulated in accordance with the present invention,including having any of the above-disclosed admixture formulations, hasa moisture or water content of at least 7% by weight and no more than15% water by total wet admixture weight when being processed by theextruder during gelatinization and/or extrusion of the admixture. Inanother preferred admixture, the admixture has a moisture or watercontent of between about 8% and about 14% water by weight. In anotherpreferred admixture, the admixture has a moisture or water content ofbetween about 8.5% and about 13% water by weight. In still anotherpreferred admixture, the admixture has a moisture or water content ofbetween 9% and 12% by admixture weight.

Where the admixture has too much water, a water reduction step can beperformed prior to or during mixing or gelatinization, such as by dryingthe admixture, to bring the total moisture or water content to a levelwithin a corresponding desired one of the 7%-15%, 8%-14%, 8.5%-13% and9%-12% water content ranges disclosed above. Where a drying step isperformed, it can be performed as a separate step using a commercialdryer, an oven, using a desiccant, or the like.

Where the admixture does not have enough water, water is added during awater adding step that can be performed in a separate water adding step,during mixing of the admixture during a mixing step, duringgelatinization of the mixed admixture during a gelatinization stepand/or during extrusion from the extruder during an extrusion step toincrease the moisture content of the admixture so the admixture has amoisture or water content of at least 7% and no greater than 18% bytotal admixture weight and preferably between 7% and 15%. In anothermethod implementation, sufficient water is added in such a water addingstep that gives the admixture a moisture content of between about 8% andabout 17% and preferably between 8% and 13%. In still another methodimplementation, sufficient water is added during the water adding stepthat gives the admixture a moisture content of between about 8.5% andabout 16% and preferably between 8.5% and 12%. Where water is added tothe admixture in a water adding step, the water can be added during themixing step, the gelatinizing step and/or during the extrusion step justprior to pellets being extruded from the extruder.

Limiting the moisture content of the admixture so it falls within acorresponding one of the desired 7%-15%, 8%-13%, 8.5%-12% and 9%-11%water content ranges set forth above is important, if not critical, toensuring that sufficient water soluble carbohydrate polymer binder isformed during gelatinization and/or extrusion so that each pelletextruded from the extruder contains a sufficient amount of water solublecarbohydrate polymer binder so that each pellet will advantageouslyclump, preferably self-clump, with one or more adjacent pellets whenwetted with moisture, liquid, urine, or water. In a preferred method ofmaking litter pellets in accordance with the present invention, limitingthe moisture content of the admixture within a corresponding one of theabove 7%-15%, 8%-13%, 8.5%-12% and 9%-11% water content ranges isimportant, if not critical, to ensuring that water soluble carbohydratepolymer binder is formed during gelatinization and/or extrusion so thateach pellet extruded from the extruder contains carbohydrate polymerbinder disposed at, along, and/or forming at least part of the outersurface of each pellet, in an amount sufficient so that binder in eachpellet will dissolve and cause the pellet to clump, preferablyself-clump, with one or more adjacent pellets when at least that pelletis wetted with moisture, liquid, urine, or water.

In another preferred method of making litter pellets in accordance withthe present invention, limiting the moisture content of the admixturewithin a corresponding one of the above 7%-15%, 8%-13%, 8.5%-12% and9%-11% water content ranges is important, if not critical, to ensuringthat starch dextrinization occurs during extrusion of the admixtureforming a sufficient amount of dextrin in each extruded pellet thatfunctions as a water soluble binder enabling each pellet toadvantageously clump, preferably self-clump, with one or more adjacentpellets when wetted with moisture, liquid, urine, or water. In one suchpreferred method, limiting the moisture content of the admixture withina corresponding one of the above 7%-15%, 8%-13%, 8.5%-12% and 9%-11%water content ranges is important, if not critical, to ensuring thatdextrin is formed during gelatinization and/or extrusion so that eachpellet extruded from the extruder contains dextrin disposed at, along,and/or forming at least part of the outer surface of each pellet, in anamount sufficient so that the dextrin dissolves in water causing eachpellet to clump, preferably self-clump, with one or more adjacentpellets when the pellet is wetted with moisture, liquid, urine, orwater.

Mixing the Admixture

In mixing any of the above admixture formulations, each constituent ofthe admixture formulation is added to a mixer or blender that preferablyis a commercially available mixer or blender, such as a ribbon blender,a paddle blender, a tumble blender or a vertical blender. A preferredmixer or blender well suited for use in mixing an admixture formulatedin accordance with the present invention is a commercially availableribbon blender. One suitable ribbon blender well suited for use is aRoss Model 42N-25 25 cubic feet, 10 horsepower ribbon blender. Anothersuitable ribbon blender well suited for use is a Ross Model 42A-52 52cubic feet, 20 horsepower ribbon blender.

The constituents, including each high carbohydrate, high starch cerealgrain, any cellulosic material(s), any sodium chloride, and any of theaforementioned additional constituents that can be added to provide thebalance or remainder of the admixture are mixed in the ribbon blenderfor a long enough time to mix them together using suitable mixingparameters to form a substantially homogeneously blended raw materialmixture. Such a ribbon blender typically has a plurality of ribbons thatrotate relative to one another at approximately 300 foot per minute tipspeeds or higher with all of the admixture constituents blended togetherfor at least 3 minutes before adding any water or before transferringthe blended raw material mixture to a feed hopper of an extruder thatfeeds the blended raw material mixture into the extruder.

In a preferred method of mixing an admixture in accordance with thepresent invention, each high carbohydrate, high starch cereal grain ofthe desired admixture formulation is blended in the ribbon blender for asuitable period of time, typically at least 3 minutes, before theblended raw material mixture is transferred, such as by a bucketelevator or the like, which elevates the blended raw material mixture tofeed it into the feed hopper of the extruder. Any cellulosic material,such as hay, beet pulp, wood fiber, or the like, is added to the blendedraw material mixture at the feed hopper enabling a mixer, such as apaddle or ribbon mixer, driven by the extruder to mix the cellulosicmaterial with the blended raw material mixture forming the dryadmixture. Any sodium chlorite, GMO, and/or any of the aforementionedadditional constituents that can be added to provide the balance orremainder of the admixture are either blended in the ribbon blender oradded to the feed hopper with the cellulosic material in forming the dryadmixture.

In a preferred method of making an admixture for extrusion into litterpellets in accordance with the present invention, water in an amountsufficient to form a wet admixture having a corresponding desired one ofthe 7%-15%, 8%-13%, 8.5%-12% and 9%-11% water content ranges is added tothe dry admixture in the extruder. If desired, at least some of thewater can be added to constituents of the admixture being blended in theribbon blender with additional water added later to the admixture in theextruder.

Gelatinizing the Admixture and Extruding the Pellets

The extruder is operated to gelatinize the wet admixture in the extrudergelatinizing the admixture into a dough or dough-like material that isthen forced under pressure by one or more rotating screws of theextruder through the extruder until extruded from an opening in a die ofan extruder head. As the gelatinized admixture is extruded as extrudateout the extruder die, a cutter, such as a rotary cutting blade rotatingat a speed of between 3,000 and 9,000 revolutions per minute, cuts theextrudate exiting the extruder into at least a plurality of pairs ofpellets having a diameter or width ranging between about two millimetersand about ten millimeters. Where the pellets are elongate or oblong,pellets are produced, having a length ranging between about twomillimeters and about ten millimeters. The size of the die opening andthe speed of the rotary cutter can be changed using routine testing andexperimentation to achieve a desired pellet size producing a pluralityof pairs of pellets well suited in size for use as cat litter. Pelletsproduced having a diameter or width ranging between about twomillimeters and about ten millimeters and a length ranging between abouttwo millimeters and about ten millimeters advantageously produce pelletssmall enough to be similar in size to conventional clay-based cat littergranules while also minimizing and preferably substantially completelypreventing tracking of litter from a litter box by an animal using thelitter box.

In a preferred method of making pellets well suited for use as pet oranimal litter, e.g., cat litter, in accordance with the presentinvention, a preferred extruder is a single screw extruder, such as anAdvantage 50 single screw extruder made by American ExtrusionInternational of 498 Prairie Hill Road of South Beloit, Ill. In one suchpreferred implementation of a method of making pellets, wet admixture isgelatinized in the extruder during a gelatinization step and thenextruded from the extruder during an extrusion step at a high enoughextrusion temperature of at least 135° Celsius (about 275° Fahrenheit)and at a high enough extrusion pressure of at least 800 pounds persquare inch (psi) at the extruder head causing carbohydrate polymerbinder to form thereby producing a plurality of pairs of pellets wellsuited for use as pet or animal litter, e.g., cat litter, havingcarbohydrate polymer binder in each pellet. Such extruder operatingconditions where the admixture is gelatinized in the extruder during agelatinization step and then extruded from the extruder during anextrusion step at an extrusion temperature of at least 135° Celsius(about 275° Fahrenheit) and at an extrusion pressure of at least 800pounds per square inch (psi) at the extruder head causes adiabaticextrusion or adiabatic extruder operating conditions formingcarbohydrate polymer binder in each pellet. Each pellet produced fromsuch a method preferably has carbohydrate polymer binder in an amountand/or pellet weight percentage in accordance with at least one of thepreferred carbohydrate polymer binder containing pellet embodimentsdescribed above.

In another such preferred method implementation, admixture isgelatinized during the gelatinization step and extruded from theextruder during the extrusion step at a high enough extrusiontemperature ranging between 135° Celsius (about 275° Fahrenheit) and170° Celsius (about 338° Fahrenheit) and at a high enough extrusionpressure ranging between 800 psi and 1,250 psi at the die of theextruder head causing carbohydrate polymer binder to form duringgelatinization and/or during extrusion producing a plurality of pairs ofpellets each having carbohydrate polymer binder in an amount and/orpellet weight percentage in accordance with at least one of thepreferred carbohydrate polymer binder containing pellet embodimentsdescribed above. In still another preferred method implementation,admixture gelatinized during the gelatinization step is extruded fromthe extruder during the extrusion step at a high enough extrusiontemperature ranging between 140° Celsius (about 284° Fahrenheit) and165° Celsius (about 330° Fahrenheit) and at a high enough extrusionpressure of between 900 psi and 1,200 psi at the die of the extruderhead producing extruded pellets in accordance with the present inventioneach having carbohydrate polymer binder in an amount and/or pelletweight percentage in accordance with at least one of the preferredcarbohydrate polymer binder containing pellet embodiments describedabove. In a further preferred method implementation, admixturegelatinized during the gelatinization step is extruded from the extruderduring the extrusion step at a high enough extrusion temperature rangingbetween 145° Celsius (about 293° Fahrenheit) and 160° Celsius (about320° Fahrenheit) and at a high enough extrusion pressure of between 900psi and 1,200 psi, and preferably about 1,100 psi, at the die of theextruder head producing extruded pellets in accordance with the presentinvention each having carbohydrate polymer binder in an amount and/orpellet weight percentage in accordance with at least one of thepreferred carbohydrate polymer binder containing pellet embodimentsdescribed above. Under each of the aforementioned extruder temperaturesand pressures, the extruder is operating under adiabatic extrusionconditions such that adiabatic extrusion is occurring causing theformation of carbohydrate polymer binder in each extruded pellet.

In one preferred implementation of a method of making pellets, wetadmixture is gelatinized in the extruder during a gelatinization stepand then extruded from the extruder during an extrusion step at a highenough extrusion temperature of at least 135° Celsius (about 275°Fahrenheit) and at a high enough extrusion pressure of at least 800pounds per square inch (psi) at the extruder head dextrinizing starchforming dextrin in each one of the plurality of pairs of pelletsproduced that is soluble in water, e.g., urine and/or moisture fromfecal matter, forming a flowable binder with at least some of the binderflowing between adjacent pellets causing them to readily clump. Suchextruder operating conditions where the admixture is gelatinized in theextruder during a gelatinization step and then extruded from theextruder during an extrusion step at an extrusion temperature of atleast 135° Celsius (about 275° Fahrenheit) and at an extrusion pressureof at least 800 pounds per square inch (psi) at the extruder headoperates the extruder under adiabatic extrusion or adiabatic extruderoperating conditions causing dextrin formation. Each pellet producedfrom such a method preferably has dextrin in an amount and/or pelletweight percentage in accordance with at least one of the preferreddextrin containing pellet embodiments described above.

In another such preferred method implementation, admixture gelatinizedduring the gelatinization step is extruded from the extruder during theextrusion step at a high enough extrusion temperature ranging between135° Celsius (about 275° Fahrenheit) and 170° Celsius (about 338°Fahrenheit) and at a high enough extrusion pressure ranging between 800psi and 1,250 psi at the die of the extruder head dextrinizing starchcausing water soluble dextrin binder to form during gelatinizationand/or during extrusion producing a plurality of pairs of pellets eachhaving dextrin in an amount and/or pellet weight percentage inaccordance with at least one of the preferred dextrin containing pelletembodiments described above. In still another preferred methodimplementation, admixture gelatinized during the gelatinization step isextruded from the extruder during the extrusion step at a high enoughextrusion temperature ranging between 140° Celsius (about 284°Fahrenheit) and 165° Celsius (about 330° Fahrenheit) and at a highenough extrusion pressure of between 900 psi and 1,200 psi at the die ofthe extruder head producing extruded pellets in accordance with thepresent invention each having dextrin binder in an amount and/or pelletweight percentage in accordance with at least one of the preferreddextrin containing pellet embodiments described above. In a furtherpreferred method implementation, admixture gelatinized during thegelatinization step is extruded from the extruder during the extrusionstep at a high enough extrusion temperature ranging between 145° Celsius(about 293° Fahrenheit) and 160° Celsius (about 320° Fahrenheit) and ata high enough extrusion pressure of between 900 psi and 1,200 psi,preferably about 1,100 psi, at the die of the extruder head producingextruded pellets in accordance with the present invention each havingdextrin binder in an amount and/or pellet weight percentage inaccordance with at least one of the preferred dextrin containing pelletembodiments described above. Under each of the aforementioned extrudertemperatures and pressures, the extruder is operating under adiabaticextrusion conditions such that adiabatic extrusion is occurring causingthe formation of dextrin in each extruded pellet.

Post-Extrusion Pellet Treatment Expansion or Puffing Control

In one preferred implementation of a method of making pellets wellsuited for use as animal or pet litter, e.g., cat litter, a pelletexpansion or puffing control step can be performed on the pellets rightafter the extrudate is extruded from the extruder and cut to intopellets by the rotary cutter to help control post-extrusion pelletpuffing or expansion. When the pellets are extruded, the pellets tend tokeep expanding or puffing for a period of time thereby decreasing theirdensity making them more porous and void filled along with increasingpellet size. When this happens, re-crystallization and/or retrogradationof starch in the pellets can undesirably accelerate.

In a preferred pellet expansion or puffing control step, pellets beingextruded are collected in a holding chamber or container, e.g. 40 gallondrum, which can be lined with a plastic liner, e.g. polyethylene orpolypropylene trash bag or the like, until at least 5 pounds of thepellets are collected in contact with one another and held for a periodof at least 5 minutes causing some pellet drying to occur before beingtransferred to be dried, treated, coated and/or packaged. In a preferredimplementation of such a pellet expansion or puffing control step, thepellets are held in the container until the average temperature of thepellets in contact with one another in the container reaches atemperature of less than 125° Celsius and preferably less than 110°Celsius before being transferred. In another preferred implementation ofsuch a pellet expansion or puffing control step, the pellets are held inthe container until the temperature of the outermost pellets reaches atemperature of less than 125° Celsius and preferably less than 110°Celsius before being transferred.

In another preferred pellet expansion or puffing control step, theextruder, preferably a single screw extruder, is operated in accordancewith the extruder operating conditions and parameters disclosed hereincausing between 100 pounds and 300 pounds of pellets to be extruded perhour that are pellets are collected immediately upon extrusion in aholding chamber or container that can include a plastic liner, e.g.polyethylene or polypropylene trash bag or the like, until at least 15pounds of the pellets are collected in contact with one another and heldfor a period of at least 5 minutes before being transferred to be dried,treated, coated and/or packaged. In a preferred implementation of such apellet expansion or puffing control step, the pellets are held in thecontainer until the average temperature of the pellets in contact withone another in the container reaches a temperature of less than 125°Celsius and preferably less than 110° Celsius before being transferred.In another preferred implementation of such a pellet expansion orpuffing control step, the pellets are held in the container until thetemperature of the outermost pellets reaches a temperature of less than125° Celsius and preferably less than 110° Celsius before beingtransferred.

In a further preferred implementation of such a pellet expansion orpuffing control step, the pellets are held in the container until theaverage temperature of the pellets in contact with one another in thecontainer reaches a temperature of less than 105° Celsius and preferablyabout 100° Celsius before being transferred. In a still furtherpreferred implementation of such a pellet expansion or puffing controlstep, the pellets are held in the container until the temperature of theoutermost pellets reaches a temperature of less than 105° Celsius andpreferably about 100° Celsius before being transferred.

Uncoated Pellets

Where the pellets produced by extrusion in accordance with theabove-discussed method in accordance with the present invention areintended to be used without agglomerating, plating or otherwise applyingany absorbent, smectite, hardening, encapsulating and/or clay-basedcoating to the pellets in a pellet coating step, the pellets can bedried in a drying step before packaging the dried pellets in a packagingstep. In one preferred implementation of a method of making pellets inaccordance with the present invention, post-extrusion processingincludes drying the pellets in an oven, a convection and/or radiant heatdryer, air drying the pellets, or the like until each pellet has amoisture content less than 10% by weight and preferably until eachpellet has a moisture content less than 5% by weight. In one such methodimplementation, the pellets are dried in such a drying step until eachpellet has a moisture content of less than 3% by weight and preferablyless than 2% by weight.

Unless air dried during the drying step, the pellets can be allowed tostabilize in a stabilizing step for a period of time after the dryingstep has been performed, preferably for a plurality of hours, before apackaging step is performed where the pellets are packaged in a packagesuitable for shipment, storage, retail display, retail sale, andconsumer or customer use. Where the pellets are air dried, anystabilizing step can be and preferably is performed concurrently withair drying before the packaging step is performed.

Retail pelletized litter package sizes contemplated include 2.5 poundpackage sizes, 5 pound package sizes, 10 pound package sizes, 15 poundpackage sizes and 20 pound package sizes. Such packaging can be in theform of paper packaging, plastic packaging, such as plastic container,plastic tub, or plastic bucket packaging, or in the form of asubstantially gas-tight bag, container, tub or bucket. Where gas-tightlysealed, the pellets can be vacuum packed or inert gas packed, e.g.,nitrogen, in order to help maximize storage and shelf life.

In one preferred packaging method and embodiment, the uncoated pelletsare packaged together with one or more packets of desiccant in thepackage to help maintain desirably low pellet moisture content below adesired moisture content level while packaged. In another preferredpackaging method and embodiment, the uncoated pellets are packagedtogether with one or more packets of desiccant in the package to helpcontrol retrogradation of starch in the pellets to help optimize shelflife as well as to help keep the pellet moisture content below a desiredlevel. Where one or more desiccant packets are placed in packagesholding uncoated pellets are used for moisture control, a suitableamount of desiccant is used per package to maintain pellet moisturecontent of less than about 5% moisture by weight. In another preferredpackaging method and embodiment, where one or more desiccant packets areplaced in packages holding uncoated pellets are used for moisturecontrol, a suitable amount of desiccant is used per package to maintainpellet moisture content of less than about 2% moisture by weight. Wheredesiccant packets are used, silica gel, activated charcoal, calciumsulfate, calcium chloride, Montmorillonite clay and/or molecular sievescan be used as a desiccant.

In another preferred packaging method and embodiment, the uncoatedpellets are packaged together with one or more packets of humectant inthe package to help maintain desired pellet moisture content above adesired moisture content level while packaged to help limit starchretrogradation to help optimize litter shelf life and litterperformance. In one such preferred packaging method and embodiment, theuncoated pellets are packaged together with one or more packets ofhumectant in the package to help reduce or substantially freeze the rateretrogradation of starch in the pellets to help optimize shelf life andmaximize litter performance. Where humectant packets are used,glycerine, sorbitol, polydextrose, or another suitable hygroscopicsubstance can be used as a humectant.

Uncoated Treated Pellets

Where the pellets produced by extrusion in accordance with theabove-discussed method in accordance with the present invention aretreated after extrusion but intended to be used without agglomerating,plating or otherwise applying any absorbent, smectite, hardening,encapsulating and/or clay-based coating to the pellets in a pelletcoating step, the pellets can be treated after extrusion with a liquid,e.g., water, and/or powder treatment that inhibits odor, inhibits ureadegradation, inhibits urease formation, inhibits bacterial growth,inhibits fungal growth, inhibits viral growth, and/or inhibits yeastgrowth. Where such a post-extrusion treatment is applied to the pellets,it can be applied or otherwise sprayed onto the pellets while thepellets are being mechanically agitated, pneumatically agitated, oragitated in another manner. If desired, the treatment of the pelletswith one or more such inhibitors can be done after or during applicationof a surfactant, a plating agent or another substance that facilitatesretention and/or absorption of the inhibitor(s) by the pellets.

Such a post-extrusion treatment step can be performed relatively soonafter extrusion, such as preferably within between 5 minutes and twohours of pellet extrusion to facilitate retention and/or absorption ofthe inhibitor(s) by the pellets. Such a post-extrusion treatment stepcan be performed prior to, during or even after the drying step, where adrying step is performed after pellet extrusion to reduce the pelletmoisture content below a desired moisture content level in accordancewith that disclosed in the preceding subsection above. If desired, thepellets can be subjected to a pellet stabilization step in accordancewith that also disclosed above in the preceding subsection.

Coated Pellets

Where the pellets produced by extrusion in accordance with theabove-discussed method in accordance with the present invention arecoated after extrusion by applying an absorbent, smectite, hardening,encapsulating and/or clay-based coating to the pellets in a pelletcoating step, the pellets can be coated within a relatively short periodof time after extrusion while the carbohydrate polymer binder and/ordextrin binder of each pellet is still sticky or tacky causing thecoating more quickly and efficiently adhere to and substantiallycompletely coat each pellet. In one preferred implementation of a pelletcoating method in accordance with the present invention, the coatingstep is performed on pellets substantially immediately after the pelletsare extruded from the extruder within no more than one half hour afterextrusion while the carbohydrate polymer binder and/or dextrin binder ofthe outer pellet surface is still sticky or tacky causing the coatingmore quickly and efficiently adhere to and substantially completely coateach pellet. In another preferred implementation of a pellet coatingmethod right after extrusion, the coating step is performed within aperiod ranging from within 5 minutes after extrusion to no longer thanone hour after extrusion while the carbohydrate polymer binder and/ordextrin binder on the outer surface of each pellet preferably is stillsomewhat sticky or tacky causing the coating more quickly andefficiently adhere to and substantially completely coat each pellet.

During the coating step, the uncoated pellets are collected andtransferred to an agglomerator, such as a commercially availableagglomerator that can be a commercially available coating tumbler or thelike. Depending on the circumstances, more than one agglomerator, e.g.,coating tumbler can be used with one coating step or one part of thecoating step being performed on pellets in one coating tumbler beforethe partially coated pellets are transferred to another coating tumblerwhere another coating step or another part of the coating step isperformed.

During the coating step, a powdered coating in accordance with thatdisclosed above in the LITTER PELLET COATING AND COATING METHODS sectionis applied to the pellets using one or more of the coating methods alsodisclosed above in the LITTER PELLET COATING AND COATING METHODSsection. Doing so coats each pellet with a coating that can be of anabsorptive composition that not only substantially completelyencapsulates each pellet but which also increases the crush strength andhardness of each pellet causing a cat to view such coated pellets as ifthey were substantially the same as granules of conventional clay-based,e.g., bentonite containing, cat litter.

Where the coating is applied together with a liquid, e.g., water, duringthe coating step, such as by being either dissolved and/or entrained inthe liquid used to apply the coating, the liquid can help tackify thecarbohydrate polymer binder and/or dextrin binder containing outersurface of each pellet helping the coating to adhere to each pelletduring the coating step. Such a liquid can include a substance orcomponent that either helps to cause the coating to adhere to eachpellet and/or helps tackify the carbohydrate polymer binder and/ordextrin binder containing outer surface to help cause the coating toadhere to each pellet.

Once the coating is applied, the coated pellets can be subjected to adrying step and/or stabilization step, such as discussed above, beforethe pellets are packaged in packaging in accordance with that discussedabove. Such packaging can also include one or more packets of desiccantand/or humectant packaged together with the coated pellets to helpcontrol pellet moisture and/or limit starch retrogradation helping tooptimize shelf life and litter performance.

Coated Treated Pellets

If desired, extruded pellets can be treated and coated including asrespectively discussed in the above UNCOATED TREATED PELLETS subsectionwith any one or more of the coating formulations disclosed above in theLITTER PELLET COATING AND COATING METHODS section set forth above and inthe above COATED PELLETS subsection with any one or more of thetreatments also disclosed above in the same LITTER PELLET COATING ANDCOATING METHODS section. Any treatment step can be performed prior to orduring the coating step. Once the coating and treatment steps have beenperformed, the coated pellets can be subjected to a drying step and/orstabilization step, such as discussed above, before the pellets arepackaged in packaging in accordance with that discussed above. Suchpackaging can also include one or more packets of desiccant and/orhumectant packaged together with the coated pellets to help controlpellet moisture and/or limit starch retrogradation helping to optimizeshelf life and litter performance.

Preferred Litter Pellet Formulations and Methods First PelletFormulation and Method

A first preferred admixture for extruding pellets well suited for use aspet or animal litter is corn-based and formed of the followingconstituents:

Cornmeal 70%-80% Cellulosic Material 20%-30% Total Mixture (beforeadding water) 100% Water (Liters per 100 lbs of Admixture) 4.7-5.5

The cornmeal can be coarsely ground or finely ground as known in theindustry. The cornmeal can be degermed cornmeal or whole grain cornmealmade of yellow corn or another suitable corn or maize. Suitablecornmeals include CCM 260 and/or YCM 260 milled cornmeals commerciallyavailable from Bunge North America of 11720 Borman Drive, St. Louis, Mo.The cornmeal has at least 70% carbohydrate content by cornmeal weightand at least 60% starch by cornmeal weight. Another preferred cornmealwell suited for use in such a pellet formulation has at least 75%carbohydrate content by cornmeal weight and at least 65% starch bycornmeal weight. The cornmeal has at least 55% amylopectin and anamylose:amylopectin ratio of between 10:90 and 45:55. Another preferredcornmeal has at least 60% amylopectin and an amylose:amylopectin ratioof between 15:85 and 40:60. Another preferred cornmeal has anamylose:amylopectin ratio of between 20:80 and 35:65.

The cellulosic material contains at least 20% cellulose by cellulosicmaterial weight. One preferred cellulose material is hay, such asalfalfa hay, which is ground or milled, such as with a hammer mill, tocomminute the hay into smaller size particles preferably having a meshsize of 20 mesh or larger. Another preferred cellulose material is beetpulp and/or wood fiber that is comminuted if needed such that itsparticles have a mesh size of 20 mesh or larger. Between 4.7 liters and5.5 liters of water are added for every 100 pounds of the total mixturesuch that the wet admixture has a moisture content ranging between about9.0% and about 11.0% and preferably between 9.4% and 10.8% of wetadmixture weight.

The corn meal is mixed, preferably in a ribbon blender for a suitableamount of time in a first mixing step to blend these dry raw materialstogether before transferring the blended dry raw mixture into a hopperof an extruder that preferably is a single screw extruder like theAdvantage 50 extruder discussed above. As the blended dry raw corn mealmixture is transferred into the extruder hopper, the cellulosic materialis added to the blended mixture mixing everything together in a secondmixing step forming a dry admixture to which water is added in a wateradding step before undergoing gelatinization in the extruder. Ifdesired, at least some water can be added during mixing or blending ofthe cornmeal before the cornmeal is mixed or blended with the cellulosicmaterial to activate one or more of starches, proteins, lipids, sugarsor the like in the cornmeal.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 0.5% and 2% ofpellet weight, between 2% and 10% of pellet weight, between 3% and 10%of pellet weight, between 4% and 12% of pellet, and/or between 5% and15% of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 0.25% and2% of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of at least 135° Celsius (about275° Fahrenheit) and at an extrusion pressure of at least 800 pounds persquare inch (psi) at the extruder head extruding the gelatinizedadmixture out an extrusion die having a die opening of between 0.03inches and 0.1 inches. Operating under these extrusion parameters and/orthe extrusion parameters disclosed below, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under these extrusionparameters and/or the extrusion parameters disclosed below, uncoatedpellets having a width or diameter of between about 2.5 millimeters and3.5 millimeters and a length of between 3.0 and 3.9 millimeters wereproduced using a 0.1 inch extruder head die opening.

Where the extruder is a single screw extruder, such a single screwextruder preferably is operated at an extrusion temperature of between135° Celsius (about 275° Fahrenheit) and 170° Celsius (about 338°Fahrenheit) and at an extrusion pressure of between 800 psi and 1,250psi. In another preferred set of extruder operating parameters, such asingle screw extruder is operated at an extrusion temperature of between140° Celsius (about 284° Fahrenheit) and 165° Celsius (about 330°Fahrenheit) and at an extrusion pressure of between 900 psi and 1,200psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 160° Celsius (about 320° Fahrenheit)and at an extrusion pressure of between 900 psi and 1,200 psi(preferably about 1,100 psi, i.e. within ±5% of 1,100 psi). The use ofan extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under such extrusionparameters, uncoated pellets having a width or diameter of between about2.5 millimeters and 3.5 millimeters and a length of between 3.0 and 3.9millimeters were produced using a 0.1 inch extruder head die opening.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate, andno more than 8% coating formulation weight of silica, e.g., crystallinesilica.

After coating, round or generally cylindrical pellets produced using a0.3 inch extruder head die opening have a width or diameter rangingbetween about 1.6 millimeters and 3.2 millimeters and a length ofbetween 1.6 and 3.5 millimeters. After coating, round or generallycylindrical pellets produced using a 0.1 inch extruder head die openinghave a width or diameter of between about 2.6 millimeters and 4.5millimeters and a length of between 3.1 and 4.9 millimeters. Coatedpellets of such size advantageously have a size similar to that ofconventional granular clay-based cat litter and water absorption of atleast 80% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Second Pellet Formulation and Method

A second preferred admixture for extruding pellets well suited for useas pet or animal litter also is corn-based and formed of the followingconstituents:

Cornmeal 70%-80% Cellulosic Material 20%-30% Total Mixture (beforeadding water) 100% Water (Liters per 100 lbs of Admixture) 4.9-5.2

The cornmeal can be coarsely ground or finely ground as known in theindustry. The cornmeal can be degermed cornmeal or whole grain cornmealmade of yellow corn or another suitable corn or maize. The cornmeal canbe a mixture of degermed cornmeal and whole grain cornmeal. Suitablecornmeals include CCM 260 and/or YCM 260 milled cornmeals commerciallyavailable from Bunge North America of 11720 Borman Drive, St. Louis, Mo.The cornmeal has at least 70% carbohydrate content by cornmeal weightand at least 60% starch by cornmeal weight. Another preferred cornmealwell suited for use in such a pellet formulation has at least 75%carbohydrate content by cornmeal weight and at least 65% starch bycornmeal weight. The cornmeal has at least 55% amylopectin and anamylose:amylopectin ratio of between 10:90 and 45:55. Another preferredcornmeal has at least 60% amylopectin and an amylose:amylopectin ratioof between 15:85 and 40:60. Another preferred cornmeal has anamylose:amylopectin ratio of between 20:80 and 35:65.

The cellulosic material contains at least 20% cellulose by cellulosicmaterial weight. One preferred cellulose material is hay, such asalfalfa hay, which is ground or milled, such as with a hammer mill, tocomminute the hay into smaller size particles preferably having a meshsize of 20 mesh or larger. Another preferred cellulose material is beetpulp and/or wood fiber that is comminuted if needed such that itsparticles have a mesh size of 20 mesh or larger. Between 4.9 liters and5.2 liters of water are added for every 100 pounds of the total mixturesuch that the wet admixture has a moisture content ranging between about9.5% and about 10.5% and preferably between 9.7% and 10.3% of wetadmixture weight.

The corn meal and/or corn flour is mixed together, preferably in aribbon blender for a suitable amount of time in a first mixing step toblend these dry raw materials together before transferring the blendeddry raw mixture into a hopper of an extruder that preferably is a singlescrew extruder like the Advantage 50 extruder discussed above. As theblended dry raw corn meal and/or corn meal mixture is transferred intothe extruder hopper, the cellulosic material, preferably hay, is addedto the blended mixture mixing everything together in a second mixingstep forming a dry admixture to which water is added in a water addingstep before undergoing gelatinization in the extruder. If desired, atleast some water can be added during mixing or blending of the cornmealbefore the cornmeal is mixed or blended with the cellulosic material toactivate one or more of starches, proteins, lipids, sugars or the likein the cornmeal.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 0.5% and 2% ofpellet weight, between 2% and 10% of pellet weight, between 3% and 10%of pellet weight, between 4% and 12% of pellet, and/or between 5% and15% of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 0.5% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of between 140° Celsius (about 284°Fahrenheit) and 170° Celsius (about 338° Fahrenheit) and at an extrusionpressure of between 900 psi and 1,200 psi at the extruder head extrudingthe gelatinized admixture out an extrusion die having a die opening ofbetween 0.03 inches and 0.1 inches. Where the extruder is a single screwextruder, such a single screw extruder preferably is operated at anextrusion temperature of between 140° Celsius (about 284° Fahrenheit)and 165° Celsius (about 330° Fahrenheit) and at an extrusion pressure ofbetween 900 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 165° Celsius (about 330° Fahrenheit)and at an extrusion pressure of between 900 psi and 1,200 psi(preferably about 1,100 psi, i.e. within ±5% of 1,100 psi). The use ofan extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under such extrusionparameters, uncoated pellets having a width or diameter of between about2.5 millimeters and 3.5 millimeters and a length of between 3.0 and 3.9millimeters were produced using a 0.1 inch extruder head die opening.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate,and/or no more than 8% coating formulation weight of silica, e.g.,crystalline silica.

After coating, round or generally cylindrical pellets produced using a0.3 inch extruder head die opening have a width or diameter rangingbetween about 1.6 millimeters and 3.2 millimeters and a length ofbetween 1.6 and 3.5 millimeters. After coating, round or generallycylindrical pellets produced using a 0.1 inch extruder head die openinghave a width or diameter of between about 2.6 millimeters and 4.5millimeters and a length of between 3.1 and 4.9 millimeters. Coatedpellets of such size advantageously have a size similar to that ofconventional granular clay-based cat litter and water absorption of atleast 80% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Third Pellet Formulation and Method

A second preferred admixture for extruding pellets well suited for useas pet or animal litter also is corn-based and formed of the followingconstituents:

Cornmeal ≈75% ± 5% Cellulosic Material ≈25% ± 5% Total Mixture (beforeadding water) 100% Water (Liters per 100 lbs of Admixture)4.7-5.5/4.9-5.2

The cornmeal can be coarsely ground or finely ground as known in theindustry. The cornmeal can be degermed cornmeal or whole grain cornmealmade of yellow corn or another suitable corn or maize. Suitablecornmeals include CCM 260 (degermed) and/or YCM 260 (whole grain) milledcornmeals commercially available from Bunge North America of 11720Borman Drive, St. Louis, Mo. A combination of degermed and whole graincornmeals can be mixed together to form the dry raw material (cornmeal)mixture. In certain instances, corn grits can be substituted for all orpart of the corn meal.

The cornmeal mixture or formulation has at least 70% carbohydratecontent by cornmeal weight and at least 60% starch by cornmeal weight.Another preferred cornmeal mixture or formulation well suited for use insuch a pellet formulation has at least 75% carbohydrate content bycornmeal weight and at least 65% starch by cornmeal weight. The cornmealhas at least 55% amylopectin and an amylose:amylopectin ratio of between10:90 and 45:55. Another preferred cornmeal has at least 60% amylopectinand an amylose:amylopectin ratio of between 15:85 and 40:60. Anotherpreferred cornmeal has an amylose:amylopectin ratio of between 20:80 and35:65.

The cellulosic material contains at least 20% cellulose by cellulosicmaterial weight. One preferred cellulose material is hay, such asalfalfa hay, which is ground or milled, such as with a hammer mill, tocomminute the hay into smaller size particles preferably having a meshsize of 20 mesh or larger. Another preferred cellulose material is beetpulp and/or wood fiber that is comminuted if needed such that itsparticles have a mesh size of 20 mesh or larger.

In one pellet formulation and pellet making method, between 4.7 litersand 5.5 liters of water are added for every 100 pounds of the totalmixture such that the wet admixture has a moisture content rangingbetween about 9.0% and about 11.0% and preferably between 9.4% and 10.8%of wet admixture weight. In another preferred pellet formulation andpellet making method, between 4.9 liters and 5.2 liters of water areadded for every 100 pounds of the total mixture such that the wetadmixture has a moisture content ranging between about 9.5% and about10.5% and preferably between 9.7% and 10.3% of wet admixture weight.

The corn meal is mixed, preferably in a ribbon blender for a suitableamount of time in a first mixing step to blend these dry raw materialstogether before transferring the blended dry raw mixture into a hopperof an extruder that preferably is a single screw extruder like theAdvantage 50 extruder discussed above. As the blended dry raw corn mealand/or corn meal mixture is transferred into the extruder hopper, thecellulosic material, preferably hay, is added to the blended mixturemixing everything together in a second mixing step forming a dryadmixture to which water is added in a water adding step beforeundergoing gelatinization in the extruder. If desired, at least somewater can be added during mixing or blending of the cornmeal before thecornmeal is mixed or blended with the cellulosic material to activateone or more of starches, proteins, lipids, sugars or the like in thecornmeal.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 1% and 2% of pelletweight, between 2% and 10% of pellet weight, between 3% and 10% ofpellet weight, between 4% and 12% of pellet, and/or between 5% and 15%of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 1% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of between 140° Celsius (about 284°Fahrenheit) and 170° Celsius (about 338° Fahrenheit) and at an extrusionpressure of between 900 psi and 1,200 psi at the extruder head extrudingthe gelatinized admixture out an extrusion die having a die opening ofbetween 0.03 inches and 0.1 inches. Where the extruder is a single screwextruder, such a single screw extruder preferably is operated at anextrusion temperature of between 140° Celsius (about 284° Fahrenheit)and 165° Celsius (about 330° Fahrenheit) and at an extrusion pressure ofbetween 900 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 165° Celsius (about 330° Fahrenheit)and at an extrusion pressure of between 900 psi and 1,200 psi(preferably about 1,100 psi, i.e. within ±5% of 1,100 psi). The use ofan extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under such extrusionparameters, uncoated pellets having a width or diameter of between about2.5 millimeters and 3.5 millimeters and a length of between 3.0 and 3.9millimeters were produced using a 0.1 inch extruder head die opening.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate,and/or no more than 8% coating formulation weight of silica, e.g.,crystalline silica.

After coating, round or generally cylindrical pellets produced using a0.3 inch extruder head die opening have a width or diameter rangingbetween about 1.6 millimeters and 3.2 millimeters and a length ofbetween 1.6 and 3.5 millimeters. After coating, round or generallycylindrical pellets produced using a 0.1 inch extruder head die openinghave a width or diameter of between about 2.6 millimeters and 4.5millimeters and a length of between 3.1 and 4.9 millimeters. Coatedpellets of such size advantageously have a size similar to that ofconventional granular clay-based cat litter and water absorption of atleast 80% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Fourth Pellet Formulation and Method

A fourth preferred admixture for extruding pellets well suited for useas pet or animal litter also is corn-based and formed of the followingconstituents:

Cornmeal ≈100% Total Mixture (before adding water) 100% Water (Litersper 100 lbs of Admixture) 4.7-5.5/4.9-5.2

The cornmeal can be coarsely ground or finely ground as known in theindustry. The cornmeal can be degermed cornmeal or whole grain cornmealmade of yellow corn or another suitable corn or maize. The cornmeal canbe a mixture of degermed cornmeal and whole grain cornmeal. Suitablecornmeals include CCM 260 and/or YCM 260 milled cornmeals commerciallyavailable from Bunge North America of 11720 Borman Drive, St. Louis, Mo.In one preferred pellet embodiment and method of pellet making,substantially all of the cornmeal is degermed yellow cornmeal thatpreferably is CCM 260 degermed yellow cornmeal. In another preferredpellet embodiment, substantially all of the cornmeal is degermed yellowcornmeal that preferably is YCM 260 whole grain yellow cornmeal. Incertain instances, corn grits can be substituted for all or part of thecorn meal.

In still another preferred pellet embodiment and method of pelletmaking, the cornmeal is made of a mixture of degermed yellow cornmeal,e.g. CCM 260, and whole grain yellow cornmeal, e.g., YCM 260, whoseweight percentages can be varied from any ratio between 75% degermedyellow cornmeal and 25% whole grain yellow cornmeal to 25% degermedyellow cornmeal and 75% whole grain yellow cornmeal. One preferreddegermed-whole grain cornmeal mixture has about 50% (±5%) degermedyellow cornmeal and about 50% (±5%) whole grain yellow cornmeal.

The cornmeal has at least 70% carbohydrate content by cornmeal weightand at least 60% starch by cornmeal weight. Another preferred cornmealwell suited for use in such a pellet formulation has at least 75%carbohydrate content by cornmeal weight and at least 65% starch bycornmeal weight. The cornmeal has at least 55% amylopectin and anamylose:amylopectin ratio of between 10:90 and 45:55. Another preferredcornmeal has at least 60% amylopectin and an amylose:amylopectin ratioof between 15:85 and 40:60. Another preferred cornmeal has anamylose:amylopectin ratio of between 20:80 and 35:65.

In one pellet formulation and pellet making method, between 4.7 litersand 5.5 liters of water are added for every 100 pounds of the totalmixture such that the wet admixture has a moisture content rangingbetween about 9.0% and about 11.0% and preferably between 9.4% and 10.8%of wet admixture weight. In another preferred pellet formulation andpellet making method, between 4.9 liters and 5.2 liters of water areadded for every 100 pounds of the total mixture such that the wetadmixture has a moisture content ranging between about 9.5% and about10.5% and preferably between 9.7% and 10.3% of wet admixture weight.

The cornmeal is mixed, preferably in a ribbon blender for a suitableamount of time in a first mixing step to blend these dry raw materialstogether forming a dry admixture before transferring the blended dry rawmixture (dry admixture) into a hopper of an extruder that preferably isa single screw extruder that preferably is the Advantage 50 extruderdiscussed above. Water is added in a water adding step before the wetadmixture undergoes gelatinization in the extruder.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 1% and 2% of pelletweight, between 2% and 10% of pellet weight, between 3% and 10% ofpellet weight, between 4% and 12% of pellet, and/or between 5% and 15%of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 1% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of at least 135° Celsius (about275° Fahrenheit) and at an extrusion pressure of at least 800 pounds persquare inch (psi) at the extruder head extruding the gelatinizedadmixture out an extrusion die having a die opening of between 0.03inches and 0.1 inches. Where the extruder is a single screw extruder,such a single screw extruder preferably is operated at an extrusiontemperature of between 135° Celsius (about 275° Fahrenheit) and 170°Celsius (about 338° Fahrenheit) and at an extrusion pressure of between800 psi and 1,250 psi. In another preferred set of extruder operatingparameters, such a single screw extruder is operated at an extrusiontemperature of between 140° Celsius (about 284° Fahrenheit) and 165°Celsius (about 330° Fahrenheit) and at an extrusion pressure of between900 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 160° Celsius (about 320° Fahrenheit)and at an extrusion pressure of between 900 psi and 1,200 psi(preferably about 1,100 psi, i.e. within ±5% of 1,100 psi). The use ofan extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under such extrusionparameters, uncoated pellets having a width or diameter of between about2.5 millimeters and 3.5 millimeters and a length of between 3.0 and 3.9millimeters were produced using a 0.1 inch extruder head die opening.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate, andno more than 8% coating formulation weight of silica, e.g., crystallinesilica.

After coating, round or generally cylindrical pellets produced using a0.3 inch extruder head die opening have a width or diameter rangingbetween about 1.6 millimeters and 3.2 millimeters and a length ofbetween 1.6 and 3.5 millimeters. After coating, round or generallycylindrical pellets produced using a 0.1 inch extruder head die openinghave a width or diameter of between about 2.6 millimeters and 4.5millimeters and a length of between 3.1 and 4.9 millimeters. Coatedpellets of such size advantageously have a size similar to that ofconventional granular clay-based cat litter and water absorption of atleast 80% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Fifth Pellet Formulation and Method

A fifth preferred admixture for extruding pellets well suited for use aspet or animal litter also is corn-based and formed of the followingconstituents:

Cornmeal 65%-85% Cellulosic Material 15%-35% Total Mixture (beforeadding water) 100% Water (Liters per 100 lbs of Admixture) 2-3/2.4-2.6

The cornmeal can be coarsely ground or finely ground as known in theindustry. The cornmeal can be degermed cornmeal or whole grain cornmealmade of yellow corn or another suitable corn or maize. The cornmeal canbe a mixture of degermed cornmeal and whole grain cornmeal. Suitablecornmeals include CCM 260 and/or YCM 260 milled cornmeals commerciallyavailable from Bunge North America of 11720 Borman Drive, St. Louis, Mo.In one preferred pellet embodiment and method of pellet making,substantially all of the cornmeal is degermed yellow cornmeal thatpreferably is CCM 260 degermed yellow cornmeal. In another preferredpellet embodiment, substantially all of the cornmeal is degermed yellowcornmeal that preferably is YCM 260 whole grain yellow cornmeal. Incertain instances, corn grits can be substituted for all or part of thecorn meal.

In still another preferred pellet embodiment and method of pelletmaking, the cornmeal is made of a mixture of degermed yellow cornmeal,e.g. CCM 260, and whole grain yellow cornmeal, e.g., YCM 260, whoseweight percentages can be varied from any ratio between 75% degermedyellow cornmeal and 25% whole grain yellow cornmeal to 25% degermedyellow cornmeal and 75% whole grain yellow cornmeal. One preferreddegermed-whole grain cornmeal mixture has about 50% (±5%) degermedyellow cornmeal and about 50% (±5%) whole grain yellow cornmeal.

The cornmeal has at least 70% carbohydrate content by cornmeal weightand at least 60% starch by cornmeal weight. Another preferred cornmealwell suited for use in such a pellet formulation has at least 75%carbohydrate content by cornmeal weight and at least 65% starch bycornmeal weight. The cornmeal has at least 55% amylopectin and anamylose:amylopectin ratio of between 10:90 and 45:55. Another preferredcornmeal has at least 60% amylopectin and an amylose:amylopectin ratioof between 15:85 and 40:60. Another preferred cornmeal has anamylose:amylopectin ratio of between 20:80 and 35:65.

In one pellet formulation and pellet making method, between 2 liters and3 liters of water are added for every 100 pounds of the total mixturesuch that the wet admixture has a moisture content no more than about10% having a moisture content ranging between about 4.0% and about 9.0%and preferably between 4.2% and 8.1% of wet admixture weight. In anotherpreferred pellet formulation and pellet making method, between 2.4liters and 2.6 liters of water are added for every 100 pounds of thetotal mixture such that the wet admixture has a moisture content rangingbetween about 4.8% and about 5.6% and preferably between 5% and 5.5% ofwet admixture weight.

The cornmeal is mixed, preferably in a ribbon blender for a suitableamount of time in a first mixing step to blend these dry raw materialstogether forming a dry admixture before transferring the blended dry rawmixture (dry admixture) into a hopper of an extruder that preferably isa single screw extruder that preferably is the Advantage 50 extruderdiscussed above. Water is added in a water adding step before the wetadmixture undergoes gelatinization in the extruder. If desired, at leastsome water can be added during mixing or blending of the cornmeal beforethe cornmeal is mixed or blended with the cellulosic material toactivate one or more of starches, proteins, lipids, sugars or the likein the cornmeal.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 0.5% and 2% ofpellet weight, between 2% and 10% of pellet weight, between 3% and 10%of pellet weight, between 4% and 12% of pellet, and/or between 5% and15% of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 0.5% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of at least 135° Celsius (about275° Fahrenheit) and at an extrusion pressure of at least 600 pounds persquare inch (psi) at the extruder head extruding the gelatinizedadmixture out an extrusion die having a die opening of between 0.01inches and 0.05 inches. Where the extruder is a single screw extruder,such a single screw extruder preferably is operated at an extrusiontemperature of between 135° Celsius (about 275° Fahrenheit) and 170°Celsius (about 338° Fahrenheit) and at an extrusion pressure of between600 psi and 1,250 psi. In another preferred set of extruder operatingparameters, such a single screw extruder is operated at an extrusiontemperature of between 140° Celsius (about 284° Fahrenheit) and 165°Celsius (about 330° Fahrenheit) and at an extrusion pressure of between600 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 160° Celsius (about 320° Fahrenheit)and at an extrusion pressure of between 600 psi and 1,200 psi. The useof an extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 2 millimeters and 4 millimeters and alength of between 2 and 4 millimeters were produced. These uncoatedpellets have a bulk density no greater than 0.4 grams per cubiccentimeter and preferably between 0.30 grams per cubic centimeter and0.35 grams per cubic centimeter (preferably about 0.317 grams per cubiccentimeter). These uncoated pellets have an ASTM oil absorbancy of atleast 1.25 grams per gram and between 1.25 grams per gram and 1.80 gramsper gram (preferably about 1.60 grams per gram). These uncoated pelletshave an ASTM water absorbancy of at least 0.7 grams per gram and between0.7 grams per gram and 0.9 grams per gram (preferably about 0.81 gramsper gram). Such uncoated pellets have a sieve analysis of between 2%-3%retained by a #5 mesh, between 25%-30% retained by a #8 mesh, between60%-75% retained by a #10 mesh, and no more than 3% retained by the pan.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate, andno more than 8% coating formulation weight of silica, e.g., crystallinesilica.

After coating, the round or generally cylindrical pellets have a widthor diameter ranging between about 2.1 millimeters and 5 millimeters anda length of between 2.1 and 5 millimeters. The coated pellets have abulk density no greater than 0.75 grams per cubic centimeter andpreferably between 0.65 grams per cubic centimeter and 0.58 grams percubic centimeter (preferably about 0.616 grams per cubic centimeter).The coated pellets have an ASTM oil absorbancy of at least 2.0 grams pergram and between 2.0 grams per gram and 2.75 grams per gram (preferablyabout 2.5 grams per gram). These coated pellets have an ASTM waterabsorbancy of at least 1.8 grams per gram and between 1.8 grams per gramand 2.25 grams per gram (preferably about 2.15 grams per gram). Suchcoated pellets have a sieve analysis of no more than 2% retained by a #5mesh, between 45%-60% retained by a #8 mesh, between 40%-50% retained bya #10 mesh with less than 1% retained by the pan.

Coated pellets of such size advantageously have a size similar to thatof conventional granular clay-based cat litter and water absorption ofat least 70% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Sixth Pellet Formulation and Method

A sixth preferred admixture for extruding pellets well suited for use aspet or animal litter also is corn-based and formed of the followingconstituents:

Cornmeal 75% ± 5% Cellulosic Material 25% ± 5% Total Mixture (beforeadding water) 100% Water (Liters per 100 lbs of Admixture) 2-3/2.4-2.6

The cornmeal can be coarsely ground or finely ground as known in theindustry. The cornmeal can be degermed cornmeal or whole grain cornmealmade of yellow corn or another suitable corn or maize. The cornmeal canbe a mixture of degermed cornmeal and whole grain cornmeal. Suitablecornmeals include CCM 260 and/or YCM 260 milled cornmeals commerciallyavailable from Bunge North America of 11720 Borman Drive, St. Louis, Mo.In one preferred pellet embodiment and method of pellet making,substantially all of the cornmeal is degermed yellow cornmeal thatpreferably is CCM 260 degermed yellow cornmeal. In another preferredpellet embodiment, substantially all of the cornmeal is degermed yellowcornmeal that preferably is YCM 260 whole grain yellow cornmeal. Incertain instances, corn grits can be substituted for all or part of thecorn meal.

In still another preferred pellet embodiment and method of pelletmaking, the cornmeal is made of a mixture of degermed yellow cornmeal,e.g. CCM 260, and whole grain yellow cornmeal, e.g., YCM 260, whoseweight percentages can be varied from any ratio between 75% degermedyellow cornmeal and 25% whole grain yellow cornmeal to 25% degermedyellow cornmeal and 75% whole grain yellow cornmeal. One preferreddegermed-whole grain cornmeal mixture has about 50% (±5%) degermedyellow cornmeal and about 50% (±5%) whole grain yellow cornmeal.

The cornmeal has at least 70% carbohydrate content by cornmeal weightand at least 60% starch by cornmeal weight. Another preferred cornmealwell suited for use in such a pellet formulation has at least 75%carbohydrate content by cornmeal weight and at least 65% starch bycornmeal weight. The cornmeal has at least 55% amylopectin and anamylose:amylopectin ratio of between 10:90 and 45:55. Another preferredcornmeal has at least 60% amylopectin and an amylose:amylopectin ratioof between 15:85 and 40:60. Another preferred cornmeal has anamylose:amylopectin ratio of between 20:80 and 35:65.

In one pellet formulation and pellet making method, between 2 liters and3 liters of water are added for every 100 pounds of the total mixturesuch that the wet admixture has a moisture content ranging between about4.0% and about 9.0% and preferably between 4.2% and 8.1% of wetadmixture weight. In another preferred pellet formulation and pelletmaking method, between 2.4 liters and 2.6 liters of water are added forevery 100 pounds of the total mixture such that the wet admixture has amoisture content ranging between about 4.8% and about 5.6% andpreferably between 5% and 5.5% of wet admixture weight.

The cornmeal is mixed, preferably in a ribbon blender for a suitableamount of time in a first mixing step to blend these dry raw materialstogether forming a dry admixture before transferring the blended dry rawmixture (dry admixture) into a hopper of an extruder that preferably isa single screw extruder that preferably is the Advantage 50 extruderdiscussed above. Water is added in a water adding step before the wetadmixture undergoes gelatinization in the extruder. If desired, at leastsome water can be added during mixing or blending of the cornmeal beforethe cornmeal is mixed or blended with the cellulosic material toactivate one or more of starches, proteins, lipids, sugars or the likein the cornmeal.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 0.5% and 2% ofpellet weight, between 2% and 10% of pellet weight, between 3% and 10%of pellet weight, between 4% and 12% of pellet, and/or between 5% and15% of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 0.5% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of at least 135° Celsius (about275° Fahrenheit) and at an extrusion pressure of at least 600 pounds persquare inch (psi) at the extruder head extruding the gelatinizedadmixture out an extrusion die having a die opening of between 0.01inches and 0.05 inches. Where the extruder is a single screw extruder,such a single screw extruder preferably is operated at an extrusiontemperature of between 135° Celsius (about 275° Fahrenheit) and 170°Celsius (about 338° Fahrenheit) and at an extrusion pressure of between600 psi and 1,250 psi. In another preferred set of extruder operatingparameters, such a single screw extruder is operated at an extrusiontemperature of between 140° Celsius (about 284° Fahrenheit) and 165°Celsius (about 330° Fahrenheit) and at an extrusion pressure of between600 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 160° Celsius (about 320° Fahrenheit)and at an extrusion pressure of between 600 psi and 1,200 psi. The useof an extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 2 millimeters and 4 millimeters and alength of between 2 and 4 millimeters were produced. These uncoatedpellets have a bulk density no greater than 0.4 grams per cubiccentimeter and preferably between 0.30 grams per cubic centimeter and0.35 grams per cubic centimeter (preferably about 0.317 grams per cubiccentimeter). These uncoated pellets have an ASTM oil absorbancy of atleast 1.25 grams per gram and between 1.25 grams per gram and 1.80 gramsper gram (preferably about 1.60 grams per gram). These uncoated pelletshave an ASTM water absorbancy of at least 0.7 grams per gram and between0.7 grams per gram and 0.9 grams per gram (preferably about 0.81 gramsper gram). Such uncoated pellets have a sieve analysis of between 2%-3%retained by a #5 mesh, between 25%-30% retained by a #8 mesh, between60%-75% retained by a #10 mesh, and no more than 3% retained by the pan.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate, andno more than 8% coating formulation weight of silica, e.g., crystallinesilica.

After coating, the round or generally cylindrical pellets have a widthor diameter ranging between about 2.1 millimeters and 5 millimeters anda length of between 2.1 and 5 millimeters. The coated pellets have abulk density no greater than 0.75 grams per cubic centimeter andpreferably between 0.65 grams per cubic centimeter and 0.58 grams percubic centimeter (preferably about 0.616 grams per cubic centimeter).The coated pellets have an ASTM oil absorbancy of at least 2.0 grams pergram and between 2.0 grams per gram and 2.75 grams per gram (preferablyabout 2.5 grams per gram). These coated pellets have an ASTM waterabsorbancy of at least 1.8 grams per gram and between 1.8 grams per gramand 2.25 grams per gram (preferably about 2.15 grams per gram). Suchcoated pellets have a sieve analysis of no more than 2% retained by a #5mesh, between 45%-60% retained by a #8 mesh, between 40%-50% retained bya #10 mesh with less than 1% retained by the pan.

Coated pellets of such size advantageously have a size similar to thatof conventional granular clay-based cat litter and water absorption ofat least 70% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Seventh Pellet Formulation and Method

A seventh preferred admixture for extruding pellets well suited for useas pet or animal litter is corn-based and formed of the followingconstituents:

Corn Flour 70%-80% Cellulosic Material 20%-30% Total Mixture (beforeadding water) 100% Water (Liters per 100 lbs of Admixture) 4.7-5.5

The corn flour can be made from degermed corn or whole grain corn madeof yellow corn, white corn, and/or another suitable corn or maize. Thecorn flour has at least 70% carbohydrate content by corn flour weightand at least 60% starch by corn flour weight. Another preferred cornflour well suited for use in such a pellet formulation has at least 75%carbohydrate content by corn flour weight and at least 65% starch bycorn flour weight. The corn flour has at least 55% amylopectin and anamylose:amylopectin ratio of between 10:90 and 45:55. Another preferredcorn flour has at least 60% amylopectin and an amylose:amylopectin ratioof between 15:85 and 40:60. Another preferred corn flour has anamylose:amylopectin ratio of between 20:80 and 35:65.

The cellulosic material contains at least 20% cellulose by cellulosicmaterial weight. One preferred cellulose material is hay, such asalfalfa hay, which is ground or milled, such as with a hammer mill, tocomminute the hay into smaller size particles preferably having a meshsize of 20 mesh or larger. Another preferred cellulose material is beetpulp and/or wood fiber that is comminuted if needed such that itsparticles have a mesh size of 20 mesh or larger. Between 4.7 liters and5.5 liters of water are added for every 100 pounds of the total mixturesuch that the wet admixture has a moisture content ranging between about9.0% and about 11.0% and preferably between 9.4% and 10.8% of wetadmixture weight.

The corn flour is mixed, preferably in a ribbon blender for a suitableamount of time in a first mixing step to blend these dry raw materialstogether before transferring the blended dry raw mixture into a hopperof an extruder that preferably is a single screw extruder like theAdvantage 50 extruder discussed above. As the blended dry raw corn flourmixture is transferred into the extruder hopper, the cellulosic materialis added to the blended mixture mixing everything together in a secondmixing step forming a dry admixture to which water is added in a wateradding step before undergoing gelatinization in the extruder. Ifdesired, at least some water can be added during mixing or blending ofthe corn flour before the corn flour is mixed or blended with thecellulosic material to activate one or more of starches, proteins,lipids, sugars or the like in the corn flour.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 0.5% and 2% ofpellet weight, between 2% and 10% of pellet weight, between 3% and 10%of pellet weight, between 4% and 12% of pellet, and/or between 5% and15% of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 0.25% and2% of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of at least 135° Celsius (about275° Fahrenheit) and at an extrusion pressure of at least 800 pounds persquare inch (psi) at the extruder head extruding the gelatinizedadmixture out an extrusion die having a die opening of between 0.03inches and 0.1 inches. Operating under these extrusion parameters and/orthe extrusion parameters disclosed below, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under these extrusionparameters and/or the extrusion parameters disclosed below, uncoatedpellets having a width or diameter of between about 2.5 millimeters and3.5 millimeters and a length of between 3.0 and 3.9 millimeters wereproduced using a 0.1 inch extruder head die opening.

Where the extruder is a single screw extruder, such a single screwextruder preferably is operated at an extrusion temperature of between135° Celsius (about 275° Fahrenheit) and 170° Celsius (about 338°Fahrenheit) and at an extrusion pressure of between 800 psi and 1,250psi. In another preferred set of extruder operating parameters, such asingle screw extruder is operated at an extrusion temperature of between140° Celsius (about 284° Fahrenheit) and 165° Celsius (about 330°Fahrenheit) and at an extrusion pressure of between 900 psi and 1,200psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 160° Celsius (about 320° Fahrenheit)and at an extrusion pressure of between 900 psi and 1,200 psi(preferably about 1,100 psi, i.e. within ±5% of 1,100 psi). The use ofan extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under such extrusionparameters, uncoated pellets having a width or diameter of between about2.5 millimeters and 3.5 millimeters and a length of between 3.0 and 3.9millimeters were produced using a 0.1 inch extruder head die opening.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate, andno more than 8% coating formulation weight of silica, e.g., crystallinesilica.

After coating, round or generally cylindrical pellets produced using a0.3 inch extruder head die opening have a width or diameter rangingbetween about 1.6 millimeters and 3.2 millimeters and a length ofbetween 1.6 and 3.5 millimeters. After coating, round or generallycylindrical pellets produced using a 0.1 inch extruder head die openinghave a width or diameter of between about 2.6 millimeters and 4.5millimeters and a length of between 3.1 and 4.9 millimeters. Coatedpellets of such size advantageously have a size similar to that ofconventional granular clay-based cat litter and water absorption of atleast 80% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Eighth Pellet Formulation and Method

An eighth preferred admixture for extruding pellets well suited for useas pet or animal litter is rice-based and formed of the followingconstituents:

Rice Meal 70%-80% Cellulosic Material 20%-30% Total Mixture (beforeadding water) 100% Water (Liters per 100 lbs of Admixture) 4.9-5.2

The rice meal can be coarsely ground or finely ground as known in theindustry. The rice meal can be degermed or whole grain rice meal made ofa short grained rice, a long grained rice and/or a wild rice. The ricemeal used can be a mixture of degermed rice meal and/or whole grain ricemeal. The rice meal has at least 70% carbohydrate content by rice mealweight and at least 60% starch by rice meal weight. Another preferredrice meal well suited for use in such a pellet formulation has at least75% carbohydrate content by rice meal weight and at least 65% starch byrice meal weight. The rice meal has at least 55% amylopectin and anamylose:amylopectin ratio of between 10:90 and 45:55. Another preferredrice meal has at least 60% amylopectin and an amylose:amylopectin ratioof between 15:85 and 40:60. Another preferred rice meal has anamylose:amylopectin ratio of between 20:80 and 35:65.

The cellulosic material contains at least 20% cellulose by cellulosicmaterial weight. One preferred cellulose material is hay, such asalfalfa hay, which is ground or milled, such as with a hammer mill, tocomminute the hay into smaller size particles preferably having a meshsize of 20 mesh or larger. Another preferred cellulose material is beetpulp and/or wood fiber that is comminuted if needed such that itsparticles have a mesh size of 20 mesh or larger. Between 4.9 liters and5.2 liters of water are added for every 100 pounds of the total mixturesuch that the wet admixture has a moisture content ranging between about9.5% and about 10.5% and preferably between 9.7% and 10.3% of wetadmixture weight.

The rice meal is mixed together, preferably in a ribbon blender for asuitable amount of time in a first mixing step to blend these dry rawmaterials together before transferring the blended dry raw mixture intoa hopper of an extruder that preferably is a single screw extruder likethe Advantage 50 extruder discussed above. As the blended dry raw ricemeal mixture is transferred into the extruder hopper, the cellulosicmaterial, preferably hay, is added to the blended mixture mixingeverything together in a second mixing step forming a dry admixture towhich water is added in a water adding step before undergoinggelatinization in the extruder. If desired, at least some water can beadded during mixing or blending of the rice meal before the rice meal ismixed or blended with the cellulosic material to activate one or more ofstarches, proteins, lipids, sugars or the like in the rice meal.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 0.5% and 2% ofpellet weight, between 2% and 10% of pellet weight, between 3% and 10%of pellet weight, between 4% and 12% of pellet, and/or between 5% and15% of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 0.5% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of between 140° Celsius (about 284°Fahrenheit) and 170° Celsius (about 338° Fahrenheit) and at an extrusionpressure of between 900 psi and 1,200 psi at the extruder head extrudingthe gelatinized admixture out an extrusion die having a die opening ofbetween 0.03 inches and 0.1 inches. Where the extruder is a single screwextruder, such a single screw extruder preferably is operated at anextrusion temperature of between 140° Celsius (about 284° Fahrenheit)and 165° Celsius (about 330° Fahrenheit) and at an extrusion pressure ofbetween 900 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 165° Celsius (about 330° Fahrenheit)and at an extrusion pressure of between 900 psi and 1,200 psi(preferably about 1,100 psi, i.e. within ±5% of 1,100 psi). The use ofan extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under such extrusionparameters, uncoated pellets having a width or diameter of between about2.5 millimeters and 3.5 millimeters and a length of between 3.0 and 3.9millimeters were produced using a 0.1 inch extruder head die opening.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate,and/or no more than 8% coating formulation weight of silica, e.g.,crystalline silica.

After coating, round or generally cylindrical pellets produced using a0.3 inch extruder head die opening have a width or diameter rangingbetween about 1.6 millimeters and 3.2 millimeters and a length ofbetween 1.6 and 3.5 millimeters. After coating, round or generallycylindrical pellets produced using a 0.1 inch extruder head die openinghave a width or diameter of between about 2.6 millimeters and 4.5millimeters and a length of between 3.1 and 4.9 millimeters. Coatedpellets of such size advantageously have a size similar to that ofconventional granular clay-based cat litter and water absorption of atleast 80% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Ninth Pellet Formulation and Method

A ninth preferred admixture for extruding pellets well suited for use aspet or animal litter is corn-based and formed of the followingconstituents:

Cornstarch ≈75% ± 5% Cellulosic Material ≈25% ± 5% Total Mixture (beforeadding water) 100% Water (Liters per 100 lbs of Admixture)4.7-5.5/4.9-5.2

The cornstarch can be coarsely ground, finely ground and/or ground toform a flour as known in the industry. If desired, the cornstarch can bemixed together with one of a cornmeal, corn grits, corn flour, ricemeal, rice grits, and/or rice flour producing a dry admixture beforemixing with the cellulosic material falling within the ≈75%±5% dryadmixture weight range. The cornstarch mixture or formulation has atleast 70% carbohydrate content by cornstarch weight and at least 60%starch by cornstarch weight. Another preferred cornstarch mixture orformulation well suited for use in such a pellet formulation has atleast 75% carbohydrate content by cornmeal weight and at least 65%starch by cornstarch weight. The cornstarch has at least 55% amylopectinand an amylose:amylopectin ratio of between 10:90 and 45:55. Anotherpreferred cornstarch has at least 60% amylopectin and anamylose:amylopectin ratio of between 15:85 and 40:60. Another preferredcornstarch has an amylose:amylopectin ratio of between 20:80 and 35:65.

The cellulosic material contains at least 20% cellulose by cellulosicmaterial weight. One preferred cellulose material is hay, such asalfalfa hay, which is ground or milled, such as with a hammer mill, tocomminute the hay into smaller size particles preferably having a meshsize of 20 mesh or larger (e.g., 30 mesh, 50 mesh, etc.). Anotherpreferred cellulose material is beet pulp and/or wood fiber that iscomminuted if needed such that its particles have a mesh size of 20 meshor larger (e.g., 30 mesh, 50 mesh, etc.).

In one pellet formulation and pellet making method, between 4.7 litersand 5.5 liters of water are added for every 100 pounds of the totalmixture such that the wet admixture has a moisture content rangingbetween about 9.0% and about 11.0% and preferably between 9.4% and 10.8%of wet admixture weight. In another preferred pellet formulation andpellet making method, between 4.9 liters and 5.2 liters of water areadded for every 100 pounds of the total mixture such that the wetadmixture has a moisture content ranging between about 9.5% and about10.5% and preferably between 9.7% and 10.3% of wet admixture weight.

The cornstarch is mixed, preferably in a ribbon blender for a suitableamount of time in a first mixing step to blend these dry raw materialstogether before transferring the blended dry raw mixture into a hopperof an extruder that preferably is a single screw extruder like theAdvantage 50 extruder discussed above. As the blended dry raw cornstarchmixture is transferred into the extruder hopper, the cellulosicmaterial, preferably hay, is added to the blended mixture mixingeverything together in a second mixing step forming a dry admixture towhich water is added in a water adding step before undergoinggelatinization in the extruder. If desired, at least some water can beadded during mixing or blending of the cornstarch before the cornstarchis mixed or blended with the cellulosic material.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 1% and 2% of pelletweight, between 2% and 10% of pellet weight, between 3% and 10% ofpellet weight, between 4% and 12% of pellet, and/or between 5% and 15%of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 1% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of between 140° Celsius (about 284°Fahrenheit) and 170° Celsius (about 338° Fahrenheit) and at an extrusionpressure of between 900 psi and 1,200 psi at the extruder head extrudingthe gelatinized admixture out an extrusion die having a die opening ofbetween 0.03 inches and 0.1 inches. Where the extruder is a single screwextruder, such a single screw extruder preferably is operated at anextrusion temperature of between 140° Celsius (about 284° Fahrenheit)and 165° Celsius (about 330° Fahrenheit) and at an extrusion pressure ofbetween 900 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 165° Celsius (about 330° Fahrenheit)and at an extrusion pressure of between 900 psi and 1,200 psi(preferably about 1,100 psi, i.e. within ±5% of 1,100 psi). The use ofan extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under such extrusionparameters, uncoated pellets having a width or diameter of between about2.5 millimeters and 3.5 millimeters and a length of between 3.0 and 3.9millimeters were produced using a 0.1 inch extruder head die opening.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate,and/or no more than 8% coating formulation weight of silica, e.g.,crystalline silica.

After coating, round or generally cylindrical pellets produced using a0.3 inch extruder head die opening have a width or diameter rangingbetween about 1.6 millimeters and 3.2 millimeters and a length ofbetween 1.6 and 3.5 millimeters. After coating, round or generallycylindrical pellets produced using a 0.1 inch extruder head die openinghave a width or diameter of between about 2.6 millimeters and 4.5millimeters and a length of between 3.1 and 4.9 millimeters. Coatedpellets of such size advantageously have a size similar to that ofconventional granular clay-based cat litter and water absorption of atleast 80% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred method of making cat litter an admixture that includesstarch is gelatinized in an extruder under sufficient pressure andtemperature causing a litter clumping agent to form that includes acarbohydrate polymer binder formed of at least some of the starch in theadmixture during extrusion from the extruder producing a plurality ofextruded litter pellets having a bulk density no greater than 0.7 gramsper cubic centimeter having carbohydrate polymer binder clumping agentthat preferably is water soluble. In one preferred method, at leastpart, if not all, of the carbohydrate polymer binder clumping agentincludes or is formed of dextrin.

During operation of the extruder in carrying out the method of makinglitter, the admixture (after any water has been added) has a moisturecontent low enough and the extruder operates at an extrusion pressureand temperature high enough to dextrinize starch in the admixture duringat least one of gelatinization and extrusion by the extruder formingdextrin in each litter pellet. In one preferred implementation of themethod, the admixture (after any water has been added, i.e. wetadmixture) has a moisture content of no more than 18% by total wetadmixture weight and the extruder extrudes the plurality of litterpellets at an extrusion pressure of at least 800 pounds per square inchand at extrusion temperature of at least 135° Celsius. Under suchextruder operating conditions, the extruder operates under adiabaticextruder operating conditions during extruding the plurality of litterpellets.

One such method of making litter produces litter pellets each having atleast 0.1% dextrin by weight. Another such method produces litterpellets each having at least 2% dextrin by weight. Still another suchmethod produces litter pellets each having between 0.1% and 5% dextrinby weight. Another such method produces litter pellets each havingbetween 2% and 10% dextrin by weight.

One preferred admixture well suited for use with a method of making ofmaking litter has at least one cereal grain with a high carbohydratecontent of at least 45% by cereal grain weight. Such an admixture can beformed of at least 70% by dry admixture weight of at least one cerealgrain having a high carbohydrate content of at least 45% by cereal grainweight. When extruded in accordance with a method of making litter ofthe present invention, each one of the plurality of litter pelletsproduced has at least 1% of carbohydrate polymer clumping agent byuncoated pellet weight and preferably between 1% and 10% carbohydratepolymer clumping agent with at least some of the carbohydrate polymerclumping agent being water soluble.

One such preferred admixture (after any water has been added, i.e. wetadmixture) has a moisture content of no more than about 10% by total wetadmixture weight and the extruder extrudes the plurality of litterpellets at an extrusion pressure of at least 600 pounds per square inchand at extrusion temperature of at least 135° Celsius. The admixture canbe made of a dry admixture formed of at least 70% by dry admixtureweight of at least one cereal grain having a high carbohydrate contentof at least 65% by cereal grain weight and having a high starch contentof at least 60% by cereal grain weight. One such preferred dry admixturehas at least 70% corn by dry admixture weight (before any water is addedto the admixture) with suitable sources of corn including at least ofcorn grits, corn meal, corn flour and corn starch and which can includea blend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

Another preferred admixture (after any water has been added, i.e. wetadmixture) producing extruded litter pellets having between 1% and 10%carbohydrate polymer binder clumping agent by pellet weight has amoisture content of no more than about 18% by total wet admixture weightand the extruder extrudes the plurality of litter pellets at anextrusion pressure of at least 800 pounds per square inch and atextrusion temperature of at least 135° Celsius. The admixture can bemade of a dry admixture formed of at least 70% by dry admixture weightof at least one cereal grain having a high carbohydrate content of atleast 65% by cereal grain weight and having a high starch content of atleast 60% by cereal grain weight. One such preferred dry admixture hasat least 70% corn by dry admixture weight (before any water is added tothe admixture) with suitable sources of corn including at least of corngrits, corn meal, corn flour and corn starch and which can include ablend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

Another preferred admixture (after any water has been added, i.e. wetadmixture) producing extruded litter pellets having between 1% and 10%carbohydrate polymer binder clumping agent by pellet weight has amoisture content of no more than about 15% by total wet admixture weightand the extruder extrudes the plurality of litter pellets at anextrusion pressure of at least 900 pounds per square inch and atextrusion temperature of at least 140° Celsius. The admixture can bemade of a dry admixture formed of at least 70% by dry admixture weightof at least one cereal grain having a high carbohydrate content of atleast 65% by cereal grain weight and having a high starch content of atleast 60% by cereal grain weight. One such preferred dry admixture hasat least 70% corn by dry admixture weight (before any water is added tothe admixture) with suitable sources of corn including at least of corngrits, corn meal, corn flour and corn starch and which can include ablend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

In a preferred method of making the litter, the extruder extrudespellets having at least 1% of the carbohydrate polymer binder clumpingagent by pellet weight at an extrusion pressure of between 900 poundsper square inch and 1,200 pounds per square inch and at an extrusiontemperature of between 140° Celsius and 165° Celsius. Such a methodproduces litter pellets with at least some of the carbohydrate polymerbinder clumping agent being water soluble. A preferred dry admixture foruse in an extruder under such extruder operating conditions has at least70% corn by dry admixture weight (before any water is added to theadmixture) with suitable sources of corn including at least of corngrits, corn meal, corn flour and corn starch and which can include ablend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

In another preferred method of making the litter, the extruder extrudespellets at an extrusion pressure of between 900 pounds per square inchand 1,200 pounds per square inch and at an extrusion temperature ofbetween 140° Celsius and 165° Celsius producing litter pellets eachhaving at least some carbohydrate polymer binder clumping agent with atleast some of the carbohydrate polymer binder clumping agent being watersoluble and which can be formed of water soluble dextrin. A preferreddry admixture for use in an extruder under such extruder operatingconditions has at least 70% corn by dry admixture weight (before anywater is added to the admixture) with suitable sources of corn includingat least of corn grits, corn meal, corn flour and corn starch and whichcan include a blend or mixture of more than one of corn grits, cornmeal, corn flour and corn starch. Each litter pellet can have asmectite-containing coating that can be formed of bentonite.

Such a preferred method of making the litter, the extruder extrudespellets at an extrusion pressure of between 900 pounds per square inchand 1,200 pounds per square inch and at an extrusion temperature ofbetween 140° Celsius and 165° Celsius causing starch dextrinization tooccur during one of gelatinizing and extruding of the litter pelletsforming at least some dextrin in each extruded litter pellet. Theadmixture can be made of a dry admixture formed of at least 70% by dryadmixture weight of at least one cereal grain having a high carbohydratecontent of at least 65% by cereal grain weight and having a high starchcontent of at least 60% by cereal grain weight. Suitable sources of thecereal grain include at least of corn grits, corn meal, corn flour andcorn starch and which can include a blend or mixture of more than one ofcorn grits, corn meal, corn flour and corn starch. One such method ofmaking litter produces litter pellets each having at least 0.1% dextrinby weight. Another such method produces litter pellets each having atleast 2% dextrin by weight. Still another such method produces litterpellets each having between 0.1% and 5% dextrin by weight. Another suchmethod produces litter pellets each having between 2% and 10% dextrin byweight. Each litter pellet can have a smectite-containing coating thatcan be formed of bentonite.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Tenth Pellet Formulation and Method

A tenth preferred admixture for extruding pellets well suited for use aspet or animal litter is rice-based and formed of the followingconstituents:

Rice Meal ≈100% Total Mixture (before adding water) 100% Water (Litersper 100 lbs of Admixture) 4.7-5.5/4.9-5.2

The rice meal can be coarsely ground or finely ground as known in theindustry. The rice meal can be degermed rice meal or whole grain ricemeal made of short grain rice, long grain rice, wild rice or anothersuitable type of rice. The rice meal used can be a mixture ofcommercially available degermed rice meal and whole grain rice meal. Instill another preferred pellet embodiment and method of pellet making,the cornmeal is made of a mixture of degermed rice meal and whole grainrice meal whose weight percentages can be varied from any ratio between100% degermed rice meal and 0% whole grain rice meal to 0% degermed ricemeal and 100% whole grain rice meal. One preferred degermed-whole grainrice meal mixture has about 50% (±5%) degermed rice meal and about 50%(±5%) whole grain rice meal.

The rice meal has at least 70% carbohydrate content by rice meal weightand at least 60% starch by rice meal weight. Another preferred rice mealwell suited for use in such a pellet formulation has at least 75%carbohydrate content by rice meal weight and at least 65% starch by ricemeal weight. The rice meal has at least 55% amylopectin and anamylose:amylopectin ratio of between 10:90 and 45:55. Another preferredrice meal has at least 60% amylopectin and an amylose:amylopectin ratioof between 15:85 and 40:60. Another preferred rice meal has anamylose:amylopectin ratio of between 20:80 and 35:65.

In one pellet formulation and pellet making method, between 4.7 litersand 5.5 liters of water are added for every 100 pounds of the totalmixture such that the wet admixture has a moisture content rangingbetween about 9.0% and about 11.0% and preferably between 9.4% and 10.8%of wet admixture weight. In another preferred pellet formulation andpellet making method, between 4.9 liters and 5.2 liters of water areadded for every 100 pounds of the total mixture such that the wetadmixture has a moisture content ranging between about 9.5% and about10.5% and preferably between 9.7% and 10.3% of wet admixture weight.

The rice meal is mixed, preferably in a ribbon blender for a suitableamount of time in a first mixing step to blend these dry raw materialstogether forming a dry admixture before transferring the blended dry rawmixture (dry admixture) into a hopper of an extruder that preferably isa single screw extruder that preferably is the Advantage 50 extruderdiscussed above. Water is added in a water adding step before the wetadmixture undergoes gelatinization in the extruder.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 1% and 2% of pelletweight, between 2% and 10% of pellet weight, between 3% and 10% ofpellet weight, between 4% and 12% of pellet, and/or between 5% and 15%of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 1% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of at least 135° Celsius (about275° Fahrenheit) and at an extrusion pressure of at least 800 pounds persquare inch (psi) at the extruder head extruding the gelatinizedadmixture out an extrusion die having a die opening of between 0.03inches and 0.1 inches. Where the extruder is a single screw extruder,such a single screw extruder preferably is operated at an extrusiontemperature of between 135° Celsius (about 275° Fahrenheit) and 170°Celsius (about 338° Fahrenheit) and at an extrusion pressure of between800 psi and 1,250 psi. In another preferred set of extruder operatingparameters, such a single screw extruder is operated at an extrusiontemperature of between 140° Celsius (about 284° Fahrenheit) and 165°Celsius (about 330° Fahrenheit) and at an extrusion pressure of between900 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 160° Celsius (about 320° Fahrenheit)and at an extrusion pressure of between 900 psi and 1,200 psi(preferably about 1,100 psi, i.e. within ±5% of 1,100 psi). The use ofan extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 1.5 millimeters and 2.2 millimetersand a length of between 1.5 and 2.5 millimeters were produced using a0.03 inch extruder head die opening. Operating under such extrusionparameters, uncoated pellets having a width or diameter of between about2.5 millimeters and 3.5 millimeters and a length of between 3.0 and 3.9millimeters were produced using a 0.1 inch extruder head die opening.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate, andno more than 8% coating formulation weight of silica, e.g., crystallinesilica.

After coating, round or generally cylindrical pellets produced using a0.3 inch extruder head die opening have a width or diameter rangingbetween about 1.6 millimeters and 3.2 millimeters and a length ofbetween 1.6 and 3.5 millimeters. After coating, round or generallycylindrical pellets produced using a 0.1 inch extruder head die openinghave a width or diameter of between about 2.6 millimeters and 4.5millimeters and a length of between 3.1 and 4.9 millimeters. Coatedpellets of such size advantageously have a size similar to that ofconventional granular clay-based cat litter and water absorption of atleast 80% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Eleventh Pellet Formulation and Method

An eleventh preferred admixture for extruding pellets well suited foruse as pet or animal litter also is rice and corn based and is formed ofthe following constituents:

Rice Meal 40%-60% Corn Starch  5%-15% Cellulosic Material 10%-40% TotalMixture (before adding water) 100% Water (Liters per 100 lbs ofAdmixture) 2-3/2.4-2.6

The rice meal can be coarsely ground or finely ground as known in theindustry. The rice meal can be degermed rice meal or whole grain ricemeal made of short grain rice, long grain rice, wild rice or anothersuitable rice. The rice meal can be a mixture of commercially availabledegermed rice meal and commercially available whole grain rice meal. Thecorn starch preferably is a commercially available corn starch that isfinely ground and which can be ground into a flour. If desired, between0.1% and 0.3% glycerol monostearate (GMS) or another suitable surfactantcan be added to the mixture either during blending of the rice meal withthe corn starch and/or when blended with the cellulosic material.

The portion of the dry admixture formed by the rice meal and corn starchhas at least 70% carbohydrate content by weight and at least 60% starchby weight. Another preferred dry admixture portion formed of the ricemeal and corn starch well suited for use in such a pellet formulationhas at least 75% carbohydrate content by weight and at least 65% starchby weight. The dry admixture portion formed of the rice meal and cornstarch has at least 55% amylopectin and an amylose:amylopectin ratio ofbetween 10:90 and 45:55. Another preferred dry admixture portion formedof the rice meal and corn starch has at least 60% amylopectin and anamylose:amylopectin ratio of between 15:85 and 40:60. Another preferreddry admixture portion formed of the rice meal and corn starch has anamylose:amylopectin ratio of between 20:80 and 35:65.

In one pellet formulation and pellet making method, between 2 liters and3 liters of water are added for every 100 pounds of the total mixturesuch that the wet admixture has a moisture content ranging between about4.0% and about 9.0% and preferably between 4.2% and 8.1% of wetadmixture weight. In another preferred pellet formulation and pelletmaking method, between 2.4 liters and 2.6 liters of water are added forevery 100 pounds of the total mixture such that the wet admixture has amoisture content ranging between about 4.8% and about 5.6% andpreferably between 5% and 5.5% of wet admixture weight.

The rice meal and corn starch is mixed, preferably in a ribbon blenderfor a suitable amount of time in a first mixing step to blend these dryraw materials together forming a dry admixture before transferring theblended dry raw mixture (dry admixture) into a hopper of an extruderthat preferably is a single screw extruder that preferably is theAdvantage 50 extruder discussed above. Water is added in a water addingstep before the wet admixture undergoes gelatinization in the extruder.If desired, at least some water can be added during mixing or blendingof the rice meal and corn starch before the blended rice meal/cornstarchmixture is mixed or blended with the cellulosic material.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 0.5% and 2% ofpellet weight, between 2% and 10% of pellet weight, between 3% and 10%of pellet weight, between 4% and 12% of pellet, and/or between 5% and15% of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 0.5% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of at least 135° Celsius (about275° Fahrenheit) and at an extrusion pressure of at least 600 pounds persquare inch (psi) at the extruder head extruding the gelatinizedadmixture out an extrusion die having a die opening of between 0.01inches and 0.05 inches. Where the extruder is a single screw extruder,such a single screw extruder preferably is operated at an extrusiontemperature of between 135° Celsius (about 275° Fahrenheit) and 170°Celsius (about 338° Fahrenheit) and at an extrusion pressure of between600 psi and 1,250 psi. In another preferred set of extruder operatingparameters, such a single screw extruder is operated at an extrusiontemperature of between 140° Celsius (about 284° Fahrenheit) and 165°Celsius (about 330° Fahrenheit) and at an extrusion pressure of between600 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 160° Celsius (about 320° Fahrenheit)and at an extrusion pressure of between 600 psi and 1,200 psi. The useof an extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 2 millimeters and 4 millimeters and alength of between 2 and 4 millimeters were produced. These uncoatedpellets have a bulk density no greater than 0.4 grams per cubiccentimeter and preferably between 0.30 grams per cubic centimeter and0.35 grams per cubic centimeter (preferably about 0.317 grams per cubiccentimeter). These uncoated pellets have an ASTM oil absorbancy of atleast 1.25 grams per gram and between 1.25 grams per gram and 1.80 gramsper gram (preferably about 1.60 grams per gram). These uncoated pelletshave an ASTM water absorbancy of at least 0.7 grams per gram and between0.7 grams per gram and 0.9 grams per gram (preferably about 0.81 gramsper gram). Such uncoated pellets have a sieve analysis of between 2%-3%retained by a #5 mesh, between 25%-30% retained by a #8 mesh, between60%-75% retained by a #10 mesh, and no more than 3% retained by the pan.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate, andno more than 8% coating formulation weight of silica, e.g., crystallinesilica.

After coating, the round or generally cylindrical pellets have a widthor diameter ranging between about 2.1 millimeters and 5 millimeters anda length of between 2.1 and 5 millimeters. The coated pellets have abulk density no greater than 0.75 grams per cubic centimeter andpreferably between 0.65 grams per cubic centimeter and 0.58 grams percubic centimeter (preferably about 0.616 grams per cubic centimeter).The coated pellets have an ASTM oil absorbancy of at least 2.0 grams pergram and between 2.0 grams per gram and 2.75 grams per gram (preferablyabout 2.5 grams per gram). These coated pellets have an ASTM waterabsorbancy of at least 1.8 grams per gram and between 1.8 grams per gramand 2.25 grams per gram (preferably about 2.15 grams per gram). Suchcoated pellets have a sieve analysis of no more than 2% retained by a #5mesh, between 45%-60% retained by a #8 mesh, between 40%-50% retained bya #10 mesh with less than 1% retained by the pan.

Coated pellets of such size advantageously have a size similar to thatof conventional granular clay-based cat litter and water absorption ofat least 70% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Twelfth Pellet Formulation and Method

A twelfth preferred admixture for extruding pellets well suited for useas pet or animal litter is corn-based and formed of the followingconstituents:

Corn Meal 55%-75% Corn Starch  5%-15% Cellulosic Material 10%-30% TotalMixture (before adding water) 100% Water (Liters per 100 lbs ofAdmixture) 2-3/2.4-2.6

The cornmeal can be coarsely ground or finely ground as known in theindustry. The cornmeal can be degermed cornmeal or whole grain cornmealmade of yellow corn or another suitable corn or maize. The cornmeal canbe a mixture of degermed cornmeal and whole grain cornmeal. Suitablecornmeals include CCM 260 and/or YCM 260 milled cornmeals commerciallyavailable from Bunge North America of 11720 Borman Drive, St. Louis, Mo.In one preferred pellet embodiment and method of pellet making,substantially all of the cornmeal is degermed yellow cornmeal thatpreferably is CCM 260 degermed yellow cornmeal. In another preferredpellet embodiment, substantially all of the cornmeal is degermed yellowcornmeal that preferably is YCM 260 whole grain yellow cornmeal. Ifdesired, in certain instances, corn grits can be substituted for thecorn meal. The corn starch preferably is a commercially available cornstarch that is finely ground and which can be ground into a flour. Ifdesired, between 0.1% and 0.3% glycerol monostearate (GMS) or anothersuitable surfactant can be added to the mixture either during blendingof the rice meal with the corn starch and/or when blended with thecellulosic material.

In still another preferred pellet embodiment and method of pelletmaking, the cornmeal is made of a mixture of degermed yellow cornmeal,e.g. CCM 260, and whole grain yellow cornmeal, e.g., YCM 260, whoseweight percentages can be varied from any ratio between 75% degermedyellow cornmeal and 25% whole grain yellow cornmeal to 25% degermedyellow cornmeal and 75% whole grain yellow cornmeal. One preferreddegermed-whole grain cornmeal mixture has about 50% (±5%) degermedyellow cornmeal and about 50% (±5%) whole grain yellow cornmeal.

The portion of the admixture formed by the corn meal and corn starch hasat least 70% carbohydrate content by weight and at least 60% starch byweight. Another preferred admixture portion formed of corn meal and cornstarch well suited for use in such a pellet formulation has at least 75%carbohydrate content by weight and at least 65% starch by weight. Theadmixture portion formed of corn meal and corn starch has at least 55%amylopectin and an amylose:amylopectin ratio of between 10:90 and 45:55.Another preferred admixture portion formed of corn meal and corn starchhas at least 60% amylopectin and an amylose:amylopectin ratio of between15:85 and 40:60. Another preferred admixture portion formed of corn mealand corn starch has an amylose:amylopectin ratio of between 20:80 and35:65.

In one pellet formulation and pellet making method, between 2 liters and3 liters of water are added for every 100 pounds of the total mixturesuch that the wet admixture has a moisture content ranging between about4.0% and about 9.0% and preferably between 4.2% and 8.1% of wetadmixture weight. In another preferred pellet formulation and pelletmaking method, between 2.4 liters and 2.6 liters of water are added forevery 100 pounds of the total mixture such that the wet admixture has amoisture content ranging between about 4.8% and about 5.6% andpreferably between 5% and 5.5% of wet admixture weight.

The corn meal and corn starch is mixed, preferably in a ribbon blenderfor a suitable amount of time in a first mixing step to blend these dryraw materials together forming a dry admixture before transferring theblended dry raw mixture (dry admixture) into a hopper of an extruderthat preferably is a single screw extruder that preferably is theAdvantage 50 extruder discussed above. Water is added in a water addingstep before the wet admixture undergoes gelatinization in the extruder.If desired, at least some water can be added to the admixture portionformed of the corn meal and corn starch before blending the mixed cornmeal and corn starch with the cellulosic material.

The extruder has at least one extruder screw that is rotated during thegelatinization step and the extrusion step to first gelatinize the wetadmixture before extruding the gelatinized admixture through at leastone orifice or opening in the die of the extruder head. The extruder isoperated to produce high enough extrusion pressures and temperatures tocause formation of water soluble carbohydrate polymer binder in thegelatinized admixture either during gelatinization and/or duringextrusion so that each extruded pellet has enough water solublecarbohydrate polymer binder present that at least some of the binderdissolves when wetted by urine, fecal matter moisture, or water causingclumping of the pellet with adjacent pellets. Each pellet has acarbohydrate polymer binder content varying between 0.5% and 2% ofpellet weight, between 2% and 10% of pellet weight, between 3% and 10%of pellet weight, between 4% and 12% of pellet, and/or between 5% and15% of pellet weight in accordance with the carbohydrate polymer binderranges discussed above in the LITTER PELLET EMBODIMENTS section above.The actual carbohydrate polymer binder content or carbohydrate polymerbinder content range produced in extruded pellets depends on factorsthat include the amount of starch present in the admixture, the rationof amylose to amylopectin, the amount of water in the admixture, as wellas extruder operating conditions.

The carbohydrate polymer binder can be formed at least in part ofamylopectin and preferably includes dextrin formed as a result of theextruder being operated under extrusion pressures and temperatures thatcause starch dextrinization to occur during extrusion. In a preferredextruder operating method, the extruder is operated to produce extrusionpressure(s) and extrusion temperature(s) that cause adiabatic extrusionto occur dextrinizing starch during extrusion thereby forming dextrin ineach extruded pellet. Where starch dextrinization occurs duringextrusion, each pellet has a dextrin content varying between 0.5% and 2%of pellet weight, between 2% and 10% of pellet weight, between 3% and10% of pellet weight, between 4% and 12% of pellet, and/or between 5%and 15% of pellet weight in accordance with the dextrin ranges discussedabove in the LITTER PELLET EMBODIMENTS section above. The actual dextrincontent or dextrin content range produced in extruded pellets depends onfactors that include the amount of starch present in the admixture, theration of amylose to amylopectin, the amount of water in the admixture,as well as extruder operating conditions.

During the gelatinization step and extrusion step, the extruder isoperated at an extrusion temperature of at least 135° Celsius (about275° Fahrenheit) and at an extrusion pressure of at least 600 pounds persquare inch (psi) at the extruder head extruding the gelatinizedadmixture out an extrusion die having a die opening of between 0.01inches and 0.05 inches. Where the extruder is a single screw extruder,such a single screw extruder preferably is operated at an extrusiontemperature of between 135° Celsius (about 275° Fahrenheit) and 170°Celsius (about 338° Fahrenheit) and at an extrusion pressure of between600 psi and 1,250 psi. In another preferred set of extruder operatingparameters, such a single screw extruder is operated at an extrusiontemperature of between 140° Celsius (about 284° Fahrenheit) and 165°Celsius (about 330° Fahrenheit) and at an extrusion pressure of between600 psi and 1,200 psi.

In another preferred method, the extruder has at least one compressionscrew or at least one screw with at least one compression section orzone that is operated at an extrusion temperature of between 145°Celsius (about 293° Fahrenheit) and 160° Celsius (about 320° Fahrenheit)and at an extrusion pressure of between 600 psi and 1,200 psi. The useof an extruder with at least one compression screw or at least one screwhaving at least one compression section or zone is preferred in order tohelp maintain relatively smooth throughput through the extruder helpingto absorb variations in gelatinized admixture viscosity therebyadvantageously helping to better maintain extruded pellet uniformity.While such an extruder preferably is a single screw extruder equippedwith a compression screw or a screw with at least one compressionsection or zone, the method of making pellets in accordance with thepresent invention can be practiced using a twin screw extruder having atleast one compression screw and/or at least one screw with at least onecompression section or zone.

Operating under such extrusion parameters, uncoated pellets having awidth or diameter of between about 2 millimeters and 4 millimeters and alength of between 2 and 4 millimeters were produced. These uncoatedpellets have a bulk density no greater than 0.4 grams per cubiccentimeter and preferably between 0.30 grams per cubic centimeter and0.35 grams per cubic centimeter (preferably about 0.317 grams per cubiccentimeter). These uncoated pellets have an ASTM oil absorbancy of atleast 1.25 grams per gram and between 1.25 grams per gram and 1.80 gramsper gram (preferably about 1.60 grams per gram). These uncoated pelletshave an ASTM water absorbancy of at least 0.7 grams per gram and between0.7 grams per gram and 0.9 grams per gram (preferably about 0.81 gramsper gram). Such uncoated pellets have a sieve analysis of between 2%-3%retained by a #5 mesh, between 25%-30% retained by a #8 mesh, between60%-75% retained by a #10 mesh, and no more than 3% retained by the pan.

As discussed above, the pellets can be packaged after extrusion, driedand then packaged after extrusion, dried, stabilized and then packagedafter extrusion, treated and packaged after extrusion, treated, driedand packaged after extrusion, treated, dried, stabilized and packagedafter extrusion, coated and packaged after extrusion, coated, dried andpackaged after extrusion, treated/coated and packaged after extrusion,or treated/coated, dried and packaged after extrusion. The pellets canbe packaged together with desiccant and/or humectant as also discussedabove.

Where coated with a clay-based coating, the pellets are agglomerated,plated or otherwise coated to form a coating of at least 0.05millimeters substantially completely covering the outer surface of eachpellet. Where coated with a clay-based coating, the pellets areagglomerated, plated or otherwise coated such as in the manner describedabove in the LITTER PELLET COATING AND COATING METHODS section to form acoating of between 0.1 millimeters and 1 millimeter substantiallycompletely covering the outer surface of each pellet.

Such a clay based coating preferably includes bentonite, preferablysodium bentonite, that is comminuted, such as by grinding or the like,into a granular material or powder having a mesh size of about 20 meshor greater and preferably a mesh size of 50 mesh or greater. Such a claybased coating can have a formulation as discussed above in the LITTERPELLET COATING AND COATING METHODS section. One preferred clay basedcoating formulation has at least 70% sodium bentonite and can havebetween 70% and 100% sodium bentonite. Where the coating formulationincludes other constituents, the coating formulation can include no morethan 10% coating formulation weight of zeolite, no more than 10% coatingformulation weight of sodium bicarbonate and/or calcium bicarbonate, andno more than 8% coating formulation weight of silica, e.g., crystallinesilica.

After coating, the round or generally cylindrical pellets have a widthor diameter ranging between about 2.1 millimeters and 5 millimeters anda length of between 2.1 and 5 millimeters. The coated pellets have abulk density no greater than 0.75 grams per cubic centimeter andpreferably between 0.65 grams per cubic centimeter and 0.58 grams percubic centimeter (preferably about 0.616 grams per cubic centimeter).The coated pellets have an ASTM oil absorbancy of at least 2.0 grams pergram and between 2.0 grams per gram and 2.75 grams per gram (preferablyabout 2.5 grams per gram). These coated pellets have an ASTM waterabsorbancy of at least 1.8 grams per gram and between 1.8 grams per gramand 2.25 grams per gram (preferably about 2.15 grams per gram). Suchcoated pellets have a sieve analysis of no more than 2% retained by a #5mesh, between 45%-60% retained by a #8 mesh, between 40%-50% retained bya #10 mesh with less than 1% retained by the pan.

Coated pellets of such size advantageously have a size similar to thatof conventional granular clay-based cat litter and water absorption ofat least 70% of conventional clay-based cat litter. As a result,performance of coated litter pellets in accordance with the presentinvention is substantially the same as conventional clay-based catlitter but weighs less than half that of conventional clay-based catlitter for a given package volume or package size.

In one preferred embodiment, it is contemplated that uncoated pelletscan be packaged and sold for use as cat litter. In another preferredembodiment, the pellets are coated with a clay-based coating asdiscussed above before being packaged and sold.

Preferred Cat Litter Pellet Formulations and Methods

In one preferred method of making an admixture well suited for makingcat litter includes starch that is gelatinized in an extruder undersufficient pressure and temperature causing a litter clumping agent toform during pellet extrusion that includes a carbohydrate polymer binderformed of at least some of the starch in the admixture during extrusionfrom the extruder producing a plurality of extruded litter pelletshaving a bulk density no greater than 0.7 grams per cubic centimeterhaving carbohydrate polymer binder clumping agent that preferably iswater soluble. In one preferred method, at least part, if not all, ofthe carbohydrate polymer binder clumping agent includes or is formed ofdextrin.

During operation of the extruder in carrying out the method of makinglitter, the admixture (after any water has been added) has a moisturecontent low enough and the extruder operates at an extrusion pressureand temperature high enough to dextrinize starch in the admixture duringat least one of gelatinization and extrusion by the extruder formingdextrin in each litter pellet. In one preferred implementation of themethod, the admixture (after any water has been added, i.e. wetadmixture) has a moisture content of no more than 18% by total wetadmixture weight and the extruder extrudes the plurality of litterpellets at an extrusion pressure of at least 800 pounds per square inchand at extrusion temperature of at least 135° Celsius. Under suchextruder operating conditions, the extruder operates under adiabaticextruder operating conditions during extruding the plurality of litterpellets.

One such method of making litter produces litter pellets each having atleast 0.1% dextrin by weight. Another such method produces litterpellets each having at least 2% dextrin by weight. Still another suchmethod produces litter pellets each having between 0.1% and 5% dextrinby weight. Another such method produces litter pellets each havingbetween 2% and 10% dextrin by weight.

One preferred admixture well suited for use with a method of making ofmaking litter has at least one cereal grain with a high carbohydratecontent of at least 45% by cereal grain weight. Such an admixture can beformed of at least 70% by dry admixture weight of at least one cerealgrain having a high carbohydrate content of at least 45% by cereal grainweight. When extruded in accordance with a method of making litter ofthe present invention, each one of the plurality of litter pelletsproduced has at least 1% of carbohydrate polymer clumping agent byuncoated pellet weight and preferably between 1% and 10% carbohydratepolymer clumping agent with at least some of the carbohydrate polymerclumping agent being water soluble.

One such preferred admixture (after any water has been added, i.e. wetadmixture) has a moisture content of no more than about 10% by total wetadmixture weight and the extruder extrudes the plurality of litterpellets at an extrusion pressure of at least 600 pounds per square inchand at extrusion temperature of at least 135° Celsius. The admixture canbe made of a dry admixture formed of at least 70% by dry admixtureweight of at least one cereal grain having a high carbohydrate contentof at least 65% by cereal grain weight and having a high starch contentof at least 60% by cereal grain weight. One such preferred dry admixturehas at least 70% corn by dry admixture weight (before any water is addedto the admixture) with suitable sources of corn including at least ofcorn grits, corn meal, corn flour and corn starch and which can includea blend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

Another preferred admixture (after any water has been added, i.e. wetadmixture) producing extruded litter pellets having between 1% and 10%carbohydrate polymer binder clumping agent by pellet weight has amoisture content of no more than about 18% by total wet admixture weightand the extruder extrudes the plurality of litter pellets at anextrusion pressure of at least 800 pounds per square inch and atextrusion temperature of at least 135° Celsius. The admixture can bemade of a dry admixture formed of at least 70% by dry admixture weightof at least one cereal grain having a high carbohydrate content of atleast 65% by cereal grain weight and having a high starch content of atleast 60% by cereal grain weight. One such preferred dry admixture hasat least 70% corn by dry admixture weight (before any water is added tothe admixture) with suitable sources of corn including at least of corngrits, corn meal, corn flour and corn starch and which can include ablend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

Another preferred admixture (after any water has been added, i.e. wetadmixture) producing extruded litter pellets having between 1% and 10%carbohydrate polymer binder clumping agent by pellet weight has amoisture content of no more than about 15% by total wet admixture weightand the extruder extrudes the plurality of litter pellets at anextrusion pressure of at least 900 pounds per square inch and atextrusion temperature of at least 140° Celsius. The admixture can bemade of a dry admixture formed of at least 70% by dry admixture weightof at least one cereal grain having a high carbohydrate content of atleast 65% by cereal grain weight and having a high starch content of atleast 60% by cereal grain weight. One such preferred dry admixture hasat least 70% corn by dry admixture weight (before any water is added tothe admixture) with suitable sources of corn including at least of corngrits, corn meal, corn flour and corn starch and which can include ablend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

In a preferred method of making the litter, the extruder extrudespellets having at least 1% of the carbohydrate polymer binder clumpingagent by pellet weight at an extrusion pressure of between 900 poundsper square inch and 1,200 pounds per square inch and at an extrusiontemperature of between 140° Celsius and 165° Celsius. Such a methodproduces litter pellets with at least some of the carbohydrate polymerbinder clumping agent being water soluble. A preferred dry admixture foruse in an extruder under such extruder operating conditions has at least70% corn by dry admixture weight (before any water is added to theadmixture) with suitable sources of corn including at least of corngrits, corn meal, corn flour and corn starch and which can include ablend or mixture of more than one of corn grits, corn meal, corn flourand corn starch. Each litter pellet can be coated after extrusion with asmectite-containing coating that can be formed of bentonite.

In another preferred method of making the litter, the extruder extrudespellets at an extrusion pressure of between 900 pounds per square inchand 1,200 pounds per square inch and at an extrusion temperature ofbetween 140° Celsius and 165° Celsius producing litter pellets eachhaving at least some carbohydrate polymer binder clumping agent with atleast some of the carbohydrate polymer binder clumping agent being watersoluble and which can be formed of water soluble dextrin. A preferreddry admixture for use in an extruder under such extruder operatingconditions has at least 70% corn by dry admixture weight (before anywater is added to the admixture) with suitable sources of corn includingat least of corn grits, corn meal, corn flour and corn starch and whichcan include a blend or mixture of more than one of corn grits, cornmeal, corn flour and corn starch. Each litter pellet can have asmectite-containing coating that can be formed of bentonite.

Such a preferred method of making the litter, the extruder extrudespellets at an extrusion pressure of between 900 pounds per square inchand 1,200 pounds per square inch and at an extrusion temperature ofbetween 140° Celsius and 165° Celsius causing starch dextrinization tooccur during one of gelatinizing and extruding of the litter pelletsforming at least some dextrin in each extruded litter pellet. Theadmixture can be made of a dry admixture formed of at least 70% by dryadmixture weight of at least one cereal grain having a high carbohydratecontent of at least 65% by cereal grain weight and having a high starchcontent of at least 60% by cereal grain weight. Suitable sources of thecereal grain include at least of corn grits, corn meal, corn flour andcorn starch and which can include a blend or mixture of more than one ofcorn grits, corn meal, corn flour and corn starch. One such method ofmaking litter produces litter pellets each having at least 0.1% dextrinby weight. Another such method produces litter pellets each having atleast 2% dextrin by weight. Still another such method produces litterpellets each having between 0.1% and 5% dextrin by weight. Another suchmethod produces litter pellets each having between 2% and 10% dextrin byweight. Each litter pellet can have a smectite-containing coating thatcan be formed of bentonite.

Understandably, the present invention has been described above in termsof one or more preferred embodiments and methods. It is recognized thatvarious alternatives and modifications may be made to these embodimentsand methods that are within the scope of the present invention. Variousalternatives are contemplated as being within the scope of the presentinvention. It is also to be understood that, although the foregoingdescription and drawings describe and illustrate in detail one or morepreferred embodiments of the present invention, to those skilled in theart to which the present invention relates, the present disclosure willsuggest many modifications and constructions, as well as widelydiffering embodiments and applications without thereby departing fromthe spirit and scope of the invention

What is claimed is:
 1. A self-clumping cat litter comprising: (a) atleast 40% starch by weight of the cat litter, and (b) a carbohydratepolymer binder litter clumping agent formed during making of the catlitter.
 2. The self-clumping cat litter of claim 1 wherein thecarbohydrate polymer binder litter clumping agent comprises a watersoluble carbohydrate polymer binder formed from starch during making ofthe cat litter.
 3. The self-clumping cat litter of claim 2 wherein thewater soluble carbohydrate polymer binder is comprised of dextrin. 4.The self-clumping cat litter of claim 2 wherein the water solublecarbohydrate polymer binder is comprised of an amylopectin starch-basedcarbohydrate polymer binder.
 5. The self-clumping cat litter of claim 1comprising between 1% and 10% carbohydrate polymer binder litterclumping agent by weight of the cat litter.
 6. The self-clumping catlitter of claim 5 wherein the carbohydrate polymer binder litterclumping agent is comprised of a water soluble polymer binder.
 7. Theself-clumping cat litter of claim 5 wherein the carbohydrate polymerbinder litter clumping agent is comprised of dextrin.
 8. Theself-clumping cat litter of claim 1 wherein the cat litter is comprisedof a plurality of extruded pellets and wherein the carbohydrate polymerbinder litter clumping agent is formed during pellet extrusion.
 9. Theself-clumping cat litter of claim 8 wherein the carbohydrate polymerbinder litter clumping agent is comprised of a water soluble polymerbinder.
 10. The self-clumping cat litter of claim 10 wherein thecarbohydrate polymer binder litter clumping agent is comprised ofdextrin.
 11. The self-clumping cat litter of claim 10 wherein the watersoluble carbohydrate polymer binder is comprised of an amylopectinstarch-based carbohydrate polymer binder.
 12. The self-clumping catlitter of claim 1 wherein the starch is comprised of at least one cerealgrain having a carbohydrate content of at least 60% by cereal grainweight and a starch content of at least 45% by cereal grain weight. 13.The self-clumping cat litter of claim 12 wherein the at least one cerealgrain is comprised of one of corn, maize, rice, wheat, triticale,amaranth and sorghum.
 14. The self-clumping cat litter of claim 13wherein the at least one cereal grain is comprised of at least one ofground or comminuted corn, maize, rice, wheat, triticale, amaranth andsorghum.
 15. The self-clumping cat litter of claim 14 wherein the atleast one cereal grain is comprised of at least one of corn grits,cornmeal, corn starch, corn flour, rice grits, rice meal, rice starch,rice flour, wheat grits, wheat meal, wheat starch, wheat flour,triticale grits, triticale meal, triticale starch, triticale flour,amaranth grits, amaranth meal, amaranth starch, amaranth flour, sorghumgrits, sorghum meal, sorghum starch, and sorghum flour.
 16. Theself-clumping cat litter of claim 15 wherein the carbohydrate polymerbinder clumping agent comprises a water soluble polymer binder clumpingagent.
 17. The self-clumping cat litter of claim 16 wherein the watersoluble polymer binder clumping agent is comprised of dextrin.
 18. Theself-clumping cat litter of claim 1 further comprising a smectite. 19.The self-clumping cat litter of claim 18 when the smectite is comprisedof a bentonite.
 20. The self-clumping cat litter of claim 18 wherein thecat litter is comprised of a plurality of pellets each covered bysmectite.
 21. A self-clumping cat litter comprised of a plurality ofpellets, each pellet comprised of (a) at least one cereal graincomprised of starch, (b) a carbohydrate polymer binder litter clumpingagent, and (c) a smectite.
 22. The self-clumping cat litter of claim 21wherein the carbohydrate polymer binder litter clumping agent of eachpellet comprises a water soluble carbohydrate polymer binder.
 23. Theself-clumping cat litter of claim 22 wherein the water solublecarbohydrate polymer binder is comprised of dextrin.
 24. Theself-clumping cat litter of claim 21 wherein the at least one cerealgrain has a carbohydrate content of at least 60% by cereal grain weightand a starch content of at least 45% by cereal grain weight.
 25. Theself-clumping cat litter of claim 24 wherein the at least one cerealgrain is comprised of at least one of ground or comminuted corn, maize,rice, wheat, triticale, amaranth and sorghum.
 26. The self-clumping catlitter of claim 25 wherein the at least one cereal grain is comprised ofat least one of corn grits, cornmeal, corn starch, corn flour, ricegrits, rice meal, rice starch, rice flour, wheat grits, wheat meal,wheat starch, wheat flour, triticale grits, triticale meal, triticalestarch, triticale flour, amaranth grits, amaranth meal, amaranth starch,amaranth flour, sorghum grits, sorghum meal, sorghum starch, and sorghumflour.
 27. The self-clumping cat litter of claim 21 wherein the smectiteforms an outer layer of each pellet.
 28. The self-clumping cat litter ofclaim 27 wherein the smectite is comprised of a bentonite.
 29. Aself-clumping cat litter comprised of a plurality of extruded pellets,each extruded pellet comprised of (a) at least one cereal graincomprised of starch, (b) a water soluble carbohydrate polymer binderlitter clumping agent formed from starch during pellet extrusion, and(c) an exterior comprised of a bentonite.
 30. The self-clumping catlitter of claim 29 the at least one cereal grain has a carbohydratecontent of at least 60% by cereal grain weight and a starch content ofat least 45% by cereal grain weight.
 31. The self-clumping cat litter ofclaim 30 wherein the at least one cereal grain is comprised of ground orcomminuted corn or maize.
 32. The self-clumping cat litter of claim 31wherein the at least one cereal grain is comprised of at least one ofcorn grits, cornmeal, corn starch, and corn flour.